LibJS: Convert internal_get_own_property() to ThrowCompletionOr

Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator.cpp

@@ -1415,7 +1415,7 @@ public:
 
     if (interface.is_legacy_platform_object()) {
         generator.append(R"~~~(
-    virtual Optional<JS::PropertyDescriptor> internal_get_own_property(JS::PropertyName const&) const override;
+    virtual JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> internal_get_own_property(JS::PropertyName const&) const override;
     virtual bool internal_set(JS::PropertyName const&, JS::Value, JS::Value) override;
     virtual bool internal_define_own_property(JS::PropertyName const&, JS::PropertyDescriptor const&) override;
     virtual bool internal_delete(JS::PropertyName const&) override;
@@ -1618,7 +1618,7 @@ static JS::Value wrap_for_legacy_platform_object_get_own_property(JS::GlobalObje
             scoped_generator.append(R"~~~(
 bool @class_name@::is_named_property_exposed_on_object(JS::PropertyName const& property_name) const
 {
-    auto& vm = this->vm();
+    [[maybe_unused]] auto& vm = this->vm();
 
     // The spec doesn't say anything about the type of the property name here.
     // Numbers can be converted to a string, which is fine and what other engines do.
@@ -1636,9 +1636,7 @@ bool @class_name@::is_named_property_exposed_on_object(JS::PropertyName const& p
 
     // 2. If O has an own property named P, then return false.
     // NOTE: This has to be done manually instead of using Object::has_own_property, as that would use the overrided internal_get_own_property.
-    auto own_property_named_p = Object::internal_get_own_property(property_name);
+    auto own_property_named_p = TRY_OR_DISCARD(Object::internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     if (own_property_named_p.has_value())
         return false;
@@ -1769,7 +1767,7 @@ Optional<JS::PropertyDescriptor> @class_name@::legacy_platform_object_get_own_pr
 
         // 3. Set ignoreNamedProps to true.
         // NOTE: To reduce complexity of WrapperGenerator, this just returns early instead of keeping track of another variable.
-        return Object::internal_get_own_property(property_name);
+        return TRY_OR_DISCARD(Object::internal_get_own_property(property_name));
     }
 )~~~");
             }
@@ -1850,7 +1848,7 @@ Optional<JS::PropertyDescriptor> @class_name@::legacy_platform_object_get_own_pr
 
             // 3. Return OrdinaryGetOwnProperty(O, P).
             get_own_property_generator.append(R"~~~(
-    return Object::internal_get_own_property(property_name);
+    return TRY_OR_DISCARD(Object::internal_get_own_property(property_name));
 }
 )~~~");
         };
@@ -1979,7 +1977,7 @@ static void invoke_indexed_property_setter(JS::GlobalObject& global_object, @ful
 
         // 3.9.1. [[GetOwnProperty]], https://heycam.github.io/webidl/#legacy-platform-object-getownproperty
         scoped_generator.append(R"~~~(
-Optional<JS::PropertyDescriptor> @class_name@::internal_get_own_property(JS::PropertyName const& property_name) const
+JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> @class_name@::internal_get_own_property(JS::PropertyName const& property_name) const
 {
     // 1. Return LegacyPlatformObjectGetOwnProperty(O, P, false).
     return legacy_platform_object_get_own_property_for_get_own_property_slot(property_name);
@@ -2112,9 +2110,7 @@ bool @class_name@::internal_define_own_property(JS::PropertyName const& property
             if (!interface.extended_attributes.contains("LegacyOverrideBuiltIns")) {
                 scoped_generator.append(R"~~~(
         // NOTE: This has to be done manually instead of using Object::has_own_property, as that would use the overrided internal_get_own_property.
-        auto own_property_named_p = Object::internal_get_own_property(property_name);
+        auto own_property_named_p = TRY_OR_DISCARD(Object::internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         if (!own_property_named_p.has_value()))~~~");
             }
@@ -2181,7 +2177,7 @@ bool @class_name@::internal_define_own_property(JS::PropertyName const& property
         scoped_generator.append(R"~~~(
 bool @class_name@::internal_delete(JS::PropertyName const& property_name)
 {
-    auto& vm = this->vm();
+    [[maybe_unused]] auto& vm = this->vm();
     auto& global_object = this->global_object();
 )~~~");
 
@@ -2273,9 +2269,7 @@ bool @class_name@::internal_delete(JS::PropertyName const& property_name)
 
         scoped_generator.append(R"~~~(
     // 3. If O has an own property with name P, then:
-    auto own_property_named_p_descriptor = Object::internal_get_own_property(property_name);
+    auto own_property_named_p_descriptor = TRY_OR_DISCARD(Object::internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     if (own_property_named_p_descriptor.has_value()) {
         // 1. If the property is not configurable, then return false.

Userland/Libraries/LibJS/Runtime/ArgumentsObject.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <LibJS/Runtime/ArgumentsObject.h>
+#include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/GlobalObject.h>
 
 namespace JS {
@@ -102,10 +103,10 @@ bool ArgumentsObject::internal_delete(PropertyName const& property_name)
 }
 
 // 10.4.4.1 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-arguments-exotic-objects-getownproperty-p
-Optional<PropertyDescriptor> ArgumentsObject::internal_get_own_property(PropertyName const& property_name) const
+ThrowCompletionOr<Optional<PropertyDescriptor>> ArgumentsObject::internal_get_own_property(PropertyName const& property_name) const
 {
     // 1. Let desc be OrdinaryGetOwnProperty(args, P).
-    auto desc = Object::internal_get_own_property(property_name);
+    auto desc = Object::internal_get_own_property(property_name).release_value();
     // 2. If desc is undefined, return desc.
     if (!desc.has_value())
         return desc;

Userland/Libraries/LibJS/Runtime/ArgumentsObject.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/Object.h>
 
@@ -22,7 +23,7 @@ public:
 
     Environment& environment() { return m_environment; }
 
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const&) const override;
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const&) const override;
     virtual bool internal_define_own_property(PropertyName const&, PropertyDescriptor const&) override;
     virtual Value internal_get(PropertyName const&, Value receiver) const override;
     virtual bool internal_set(PropertyName const&, Value value, Value receiver) override;

Userland/Libraries/LibJS/Runtime/Array.cpp

@@ -7,6 +7,7 @@
 
 #include <AK/Function.h>
 #include <LibJS/Runtime/Array.h>
+#include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/Error.h>
 #include <LibJS/Runtime/GlobalObject.h>
 
@@ -157,11 +158,11 @@ bool Array::set_length(PropertyDescriptor const& property_descriptor)
 }
 
 // NON-STANDARD: Used to return the value of the ephemeral length property
-Optional<PropertyDescriptor> Array::internal_get_own_property(PropertyName const& property_name) const
+ThrowCompletionOr<Optional<PropertyDescriptor>> Array::internal_get_own_property(PropertyName const& property_name) const
 {
     auto& vm = this->vm();
     if (property_name.is_string() && property_name.as_string() == vm.names.length.as_string())
-        return PropertyDescriptor { .value = Value(indexed_properties().array_like_size()), .writable = m_length_writable, .enumerable = false, .configurable = false };
+        return { PropertyDescriptor { .value = Value(indexed_properties().array_like_size()), .writable = m_length_writable, .enumerable = false, .configurable = false } };
 
     return Object::internal_get_own_property(property_name);
 }

Userland/Libraries/LibJS/Runtime/Array.h

@@ -9,6 +9,7 @@
 #include <AK/Assertions.h>
 #include <AK/Function.h>
 #include <AK/Vector.h>
+#include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Object.h>
 
@@ -37,7 +38,7 @@ public:
     explicit Array(Object& prototype);
     virtual ~Array() override;
 
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const&) const override;
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const&) const override;
     virtual bool internal_define_own_property(PropertyName const&, PropertyDescriptor const&) override;
     virtual bool internal_delete(PropertyName const&) override;
     virtual MarkedValueList internal_own_property_keys() const override;

Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp

@@ -142,11 +142,8 @@ bool GlobalEnvironment::has_lexical_declaration(FlyString const& name) const
 // 9.1.1.4.14 HasRestrictedGlobalProperty ( N ), https://tc39.es/ecma262/#sec-hasrestrictedglobalproperty
 bool GlobalEnvironment::has_restricted_global_property(FlyString const& name) const
 {
-    auto& vm = this->vm();
     auto& global_object = m_object_record->binding_object();
-    auto existing_prop = global_object.internal_get_own_property(name);
+    auto existing_prop = TRY_OR_DISCARD(global_object.internal_get_own_property(name));
-    if (vm.exception())
-        return {};
     if (!existing_prop.has_value())
         return false;
     if (*existing_prop->configurable)
@@ -170,11 +167,8 @@ bool GlobalEnvironment::can_declare_global_var(FlyString const& name) const
 // 9.1.1.4.16 CanDeclareGlobalFunction ( N ), https://tc39.es/ecma262/#sec-candeclareglobalfunction
 bool GlobalEnvironment::can_declare_global_function(FlyString const& name) const
 {
-    auto& vm = this->vm();
     auto& global_object = m_object_record->binding_object();
-    auto existing_prop = global_object.internal_get_own_property(name);
+    auto existing_prop = TRY_OR_DISCARD(global_object.internal_get_own_property(name));
-    if (vm.exception())
-        return {};
     if (!existing_prop.has_value())
         return global_object.is_extensible();
     if (*existing_prop->configurable)
@@ -212,9 +206,10 @@ void GlobalEnvironment::create_global_function_binding(FlyString const& name, Va
 {
     auto& vm = this->vm();
     auto& global_object = m_object_record->binding_object();
-    auto existing_prop = global_object.internal_get_own_property(name);
+    auto existing_prop_or_error = global_object.internal_get_own_property(name);
-    if (vm.exception())
+    if (existing_prop_or_error.is_error())
         return;
+    auto existing_prop = existing_prop_or_error.release_value();
     PropertyDescriptor desc;
     if (!existing_prop.has_value() || *existing_prop->configurable)
         desc = { .value = value, .writable = true, .enumerable = true, .configurable = can_be_deleted };

Userland/Libraries/LibJS/Runtime/Object.cpp

@@ -269,17 +269,13 @@ bool Object::has_property(PropertyName const& property_name) const
 // 7.3.12 HasOwnProperty ( O, P ), https://tc39.es/ecma262/#sec-hasownproperty
 bool Object::has_own_property(PropertyName const& property_name) const
 {
-    auto& vm = this->vm();
-
     // 1. Assert: Type(O) is Object.
 
     // 2. Assert: IsPropertyKey(P) is true.
     VERIFY(property_name.is_valid());
 
     // 3. Let desc be ? O.[[GetOwnProperty]](P).
-    auto descriptor = internal_get_own_property(property_name);
+    auto descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 4. If desc is undefined, return false.
     if (!descriptor.has_value())
@@ -333,9 +329,7 @@ bool Object::set_integrity_level(IntegrityLevel level)
             auto property_name = PropertyName::from_value(global_object, key);
 
             // i. Let currentDesc be ? O.[[GetOwnProperty]](k).
-            auto current_descriptor = internal_get_own_property(property_name);
+            auto current_descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-            if (vm.exception())
-                return {};
 
             // ii. If currentDesc is not undefined, then
             if (!current_descriptor.has_value())
@@ -395,9 +389,7 @@ bool Object::test_integrity_level(IntegrityLevel level) const
         auto property_name = PropertyName::from_value(global_object(), key);
 
         // a. Let currentDesc be ? O.[[GetOwnProperty]](k).
-        auto current_descriptor = internal_get_own_property(property_name);
+        auto current_descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         // b. If currentDesc is not undefined, then
         if (!current_descriptor.has_value())
@@ -445,9 +437,10 @@ MarkedValueList Object::enumerable_own_property_names(PropertyKind kind) const
         auto property_name = PropertyName::from_value(global_object, key);
 
         // i. Let desc be ? O.[[GetOwnProperty]](key).
-        auto descriptor = internal_get_own_property(property_name);
+        auto descriptor_or_error = internal_get_own_property(property_name);
-        if (vm.exception())
+        if (descriptor_or_error.is_error())
             return MarkedValueList { heap() };
+        auto descriptor = descriptor_or_error.release_value();
 
         // ii. If desc is not undefined and desc.[[Enumerable]] is true, then
         if (descriptor.has_value() && *descriptor->enumerable) {
@@ -562,14 +555,14 @@ ThrowCompletionOr<bool> Object::internal_prevent_extensions()
 }
 
 // 10.1.5 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots-getownproperty-p
-Optional<PropertyDescriptor> Object::internal_get_own_property(PropertyName const& property_name) const
+ThrowCompletionOr<Optional<PropertyDescriptor>> Object::internal_get_own_property(PropertyName const& property_name) const
 {
     // 1. Assert: IsPropertyKey(P) is true.
     VERIFY(property_name.is_valid());
 
     // 2. If O does not have an own property with key P, return undefined.
     if (!storage_has(property_name))
-        return {};
+        return Optional<PropertyDescriptor> {};
 
     // 3. Let D be a newly created Property Descriptor with no fields.
     PropertyDescriptor descriptor;
@@ -603,7 +596,7 @@ Optional<PropertyDescriptor> Object::internal_get_own_property(PropertyName cons
     descriptor.configurable = attributes.is_configurable();
 
     // 9. Return D.
-    return descriptor;
+    return { descriptor };
 }
 
 // 10.1.6 [[DefineOwnProperty]] ( P, Desc ), https://tc39.es/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots-defineownproperty-p-desc
@@ -613,9 +606,7 @@ bool Object::internal_define_own_property(PropertyName const& property_name, Pro
     auto& vm = this->vm();
 
     // 1. Let current be ? O.[[GetOwnProperty]](P).
-    auto current = internal_get_own_property(property_name);
+    auto current = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 2. Let extensible be ? IsExtensible(O).
     auto extensible = is_extensible();
@@ -629,15 +620,11 @@ bool Object::internal_define_own_property(PropertyName const& property_name, Pro
 // 10.1.7 [[HasProperty]] ( P ), https://tc39.es/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots-hasproperty-p
 bool Object::internal_has_property(PropertyName const& property_name) const
 {
-    auto& vm = this->vm();
-
     // 1. Assert: IsPropertyKey(P) is true.
     VERIFY(property_name.is_valid());
 
     // 2. Let hasOwn be ? O.[[GetOwnProperty]](P).
-    auto has_own = internal_get_own_property(property_name);
+    auto has_own = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 3. If hasOwn is not undefined, return true.
     if (has_own.has_value())
@@ -666,9 +653,7 @@ Value Object::internal_get(PropertyName const& property_name, Value receiver) co
     VERIFY(property_name.is_valid());
 
     // 2. Let desc be ? O.[[GetOwnProperty]](P).
-    auto descriptor = internal_get_own_property(property_name);
+    auto descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 3. If desc is undefined, then
     if (!descriptor.has_value()) {
@@ -706,15 +691,12 @@ bool Object::internal_set(PropertyName const& property_name, Value value, Value
 {
     VERIFY(!value.is_empty());
     VERIFY(!receiver.is_empty());
-    auto& vm = this->vm();
 
     // 1. Assert: IsPropertyKey(P) is true.
     VERIFY(property_name.is_valid());
 
     // 2. Let ownDesc be ? O.[[GetOwnProperty]](P).
-    auto own_descriptor = internal_get_own_property(property_name);
+    auto own_descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 3. Return OrdinarySetWithOwnDescriptor(O, P, V, Receiver, ownDesc).
     return ordinary_set_with_own_descriptor(property_name, value, receiver, own_descriptor);
@@ -761,9 +743,7 @@ bool Object::ordinary_set_with_own_descriptor(PropertyName const& property_name,
             return false;
 
         // c. Let existingDescriptor be ? Receiver.[[GetOwnProperty]](P).
-        auto existing_descriptor = receiver.as_object().internal_get_own_property(property_name);
+        auto existing_descriptor = TRY_OR_DISCARD(receiver.as_object().internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         // d. If existingDescriptor is not undefined, then
         if (existing_descriptor.has_value()) {
@@ -811,15 +791,11 @@ bool Object::ordinary_set_with_own_descriptor(PropertyName const& property_name,
 // 10.1.10 [[Delete]] ( P ), https://tc39.es/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots-delete-p
 bool Object::internal_delete(PropertyName const& property_name)
 {
-    auto& vm = this->vm();
-
     // 1. Assert: IsPropertyKey(P) is true.
     VERIFY(property_name.is_valid());
 
     // 2. Let desc be ? O.[[GetOwnProperty]](P).
-    auto descriptor = internal_get_own_property(property_name);
+    auto descriptor = TRY_OR_DISCARD(internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 3. If desc is undefined, return true.
     if (!descriptor.has_value())
@@ -1119,9 +1095,7 @@ Object* Object::define_properties(Value properties)
         auto property_name = PropertyName::from_value(global_object, next_key);
 
         // a. Let propDesc be ? props.[[GetOwnProperty]](nextKey).
-        auto property_descriptor = props->internal_get_own_property(property_name);
+        auto property_descriptor = TRY_OR_DISCARD(props->internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         // b. If propDesc is not undefined and propDesc.[[Enumerable]] is true, then
         if (property_descriptor.has_value() && *property_descriptor->enumerable) {

Userland/Libraries/LibJS/Runtime/Object.h

@@ -95,7 +95,7 @@ public:
     virtual ThrowCompletionOr<bool> internal_set_prototype_of(Object* prototype);
     virtual ThrowCompletionOr<bool> internal_is_extensible() const;
     virtual ThrowCompletionOr<bool> internal_prevent_extensions();
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const&) const;
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const&) const;
     virtual bool internal_define_own_property(PropertyName const&, PropertyDescriptor const&);
     virtual bool internal_has_property(PropertyName const&) const;
     virtual Value internal_get(PropertyName const&, Value receiver) const;

Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp

@@ -291,9 +291,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::get_own_property_descriptor)
     auto key = vm.argument(1).to_property_key(global_object);
     if (vm.exception())
         return {};
-    auto descriptor = object->internal_get_own_property(key);
+    auto descriptor = TRY_OR_DISCARD(object->internal_get_own_property(key));
-    if (vm.exception())
-        return {};
     return from_property_descriptor(global_object, descriptor);
 }
 
@@ -315,9 +313,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::get_own_property_descriptors)
         auto property_name = PropertyName::from_value(global_object, key);
 
         // a. Let desc be ? obj.[[GetOwnProperty]](key).
-        auto desc = object->internal_get_own_property(property_name);
+        auto desc = TRY_OR_DISCARD(object->internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         // b. Let descriptor be ! FromPropertyDescriptor(desc).
         auto descriptor = from_property_descriptor(global_object, desc);
@@ -484,9 +480,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::assign)
             auto property_name = PropertyName::from_value(global_object, next_key);
 
             // 1. Let desc be ? from.[[GetOwnProperty]](nextKey).
-            auto desc = from->internal_get_own_property(property_name);
+            auto desc = TRY_OR_DISCARD(from->internal_get_own_property(property_name));
-            if (vm.exception())
-                return {};
 
             // 2. If desc is not undefined and desc.[[Enumerable]] is true, then
             if (!desc.has_value() || !*desc->enumerable)

Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp

@@ -103,7 +103,10 @@ void ObjectEnvironment::set_mutable_binding(GlobalObject& global_object, FlyStri
 
     // Note: Nothing like this in the spec, this is here to produce nicer errors instead of the generic one thrown by Object::set().
     if (!result && strict) {
-        auto property = m_binding_object.internal_get_own_property(name);
+        auto property_or_error = m_binding_object.internal_get_own_property(name);
+        if (property_or_error.is_error())
+            return;
+        auto property = property_or_error.release_value();
         if (property.has_value() && !property->writable.value_or(true)) {
             vm.clear_exception();
             vm.throw_exception<TypeError>(global_object, ErrorType::DescWriteNonWritable, name);

Userland/Libraries/LibJS/Runtime/ObjectPrototype.cpp

@@ -166,9 +166,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::property_is_enumerable)
     if (!this_object)
         return {};
     // 3. Let desc be ? O.[[GetOwnProperty]](P).
-    auto property_descriptor = this_object->internal_get_own_property(property_key);
+    auto property_descriptor = TRY_OR_DISCARD(this_object->internal_get_own_property(property_key));
-    if (vm.exception())
-        return {};
     // 4. If desc is undefined, return false.
     if (!property_descriptor.has_value())
         return Value(false);
@@ -260,9 +258,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::lookup_getter)
         return {};
 
     while (object) {
-        auto desc = object->internal_get_own_property(key);
+        auto desc = TRY_OR_DISCARD(object->internal_get_own_property(key));
-        if (vm.exception())
-            return {};
         if (desc.has_value()) {
             if (desc->is_accessor_descriptor())
                 return *desc->get ?: js_undefined();
@@ -286,9 +282,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::lookup_setter)
         return {};
 
     while (object) {
-        auto desc = object->internal_get_own_property(key);
+        auto desc = TRY_OR_DISCARD(object->internal_get_own_property(key));
-        if (vm.exception())
-            return {};
         if (desc.has_value()) {
             if (desc->is_accessor_descriptor())
                 return *desc->set ?: js_undefined();

Userland/Libraries/LibJS/Runtime/ProxyObject.cpp

@@ -231,7 +231,7 @@ ThrowCompletionOr<bool> ProxyObject::internal_prevent_extensions()
 }
 
 // 10.5.5 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-getownproperty-p
-Optional<PropertyDescriptor> ProxyObject::internal_get_own_property(const PropertyName& property_name) const
+ThrowCompletionOr<Optional<PropertyDescriptor>> ProxyObject::internal_get_own_property(const PropertyName& property_name) const
 {
     auto& vm = this->vm();
     auto& global_object = this->global_object();
@@ -242,16 +242,14 @@ Optional<PropertyDescriptor> ProxyObject::internal_get_own_property(const Proper
     // 2. Let handler be O.[[ProxyHandler]].
 
     // 3. If handler is null, throw a TypeError exception.
-    if (m_is_revoked) {
+    if (m_is_revoked)
-        vm.throw_exception<TypeError>(global_object, ErrorType::ProxyRevoked);
+        return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyRevoked);
-        return {};
-    }
 
     // 4. Assert: Type(handler) is Object.
     // 5. Let target be O.[[ProxyTarget]].
 
     // 6. Let trap be ? GetMethod(handler, "getOwnPropertyDescriptor").
-    auto trap = TRY_OR_DISCARD(Value(&m_handler).get_method(global_object, vm.names.getOwnPropertyDescriptor));
+    auto trap = TRY(Value(&m_handler).get_method(global_object, vm.names.getOwnPropertyDescriptor));
 
     // 7. If trap is undefined, then
     if (!trap) {
@@ -260,55 +258,47 @@ Optional<PropertyDescriptor> ProxyObject::internal_get_own_property(const Proper
     }
 
     // 8. Let trapResultObj be ? Call(trap, handler, « target, P »).
-    auto trap_result = TRY_OR_DISCARD(vm.call(*trap, &m_handler, &m_target, property_name_to_value(vm, property_name)));
+    auto trap_result = TRY(vm.call(*trap, &m_handler, &m_target, property_name_to_value(vm, property_name)));
 
     // 9. If Type(trapResultObj) is neither Object nor Undefined, throw a TypeError exception.
-    if (!trap_result.is_object() && !trap_result.is_undefined()) {
+    if (!trap_result.is_object() && !trap_result.is_undefined())
-        vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorReturn);
+        return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorReturn);
-        return {};
-    }
 
     // 10. Let targetDesc be ? target.[[GetOwnProperty]](P).
-    auto target_descriptor = m_target.internal_get_own_property(property_name);
+    auto target_descriptor = TRY(m_target.internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 11. If trapResultObj is undefined, then
     if (trap_result.is_undefined()) {
         // a. If targetDesc is undefined, return undefined.
         if (!target_descriptor.has_value())
-            return {};
+            return Optional<PropertyDescriptor> {};
 
         // b. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
-        if (!*target_descriptor->configurable) {
+        if (!*target_descriptor->configurable)
-            vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorNonConfigurable);
+            return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorNonConfigurable);
-            return {};
-        }
 
         // c. Let extensibleTarget be ? IsExtensible(target).
         auto extensible_target = m_target.is_extensible();
-        if (vm.exception())
+        if (auto* exception = vm.exception())
-            return {};
+            return throw_completion(exception->value());
 
         // d. If extensibleTarget is false, throw a TypeError exception.
-        if (!extensible_target) {
+        if (!extensible_target)
-            vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorUndefinedReturn);
+            return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorUndefinedReturn);
-            return {};
-        }
 
         // e. Return undefined.
-        return {};
+        return Optional<PropertyDescriptor> {};
     }
 
     // 12. Let extensibleTarget be ? IsExtensible(target).
     auto extensible_target = m_target.is_extensible();
-    if (vm.exception())
+    if (auto* exception = vm.exception())
-        return {};
+        return throw_completion(exception->value());
 
     // 13. Let resultDesc be ? ToPropertyDescriptor(trapResultObj).
     auto result_desc = to_property_descriptor(global_object, trap_result);
-    if (vm.exception())
+    if (auto* exception = vm.exception())
-        return {};
+        return throw_completion(exception->value());
 
     // 14. Call CompletePropertyDescriptor(resultDesc).
     result_desc.complete();
@@ -317,31 +307,26 @@ Optional<PropertyDescriptor> ProxyObject::internal_get_own_property(const Proper
     auto valid = is_compatible_property_descriptor(extensible_target, result_desc, target_descriptor);
 
     // 16. If valid is false, throw a TypeError exception.
-    if (!valid) {
+    if (!valid)
-        vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorInvalidDescriptor);
+        return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorInvalidDescriptor);
-        return {};
-    }
 
     // 17. If resultDesc.[[Configurable]] is false, then
     if (!*result_desc.configurable) {
         // a. If targetDesc is undefined or targetDesc.[[Configurable]] is true, then
-        if (!target_descriptor.has_value() || *target_descriptor->configurable) {
+        if (!target_descriptor.has_value() || *target_descriptor->configurable)
             // i. Throw a TypeError exception.
-            vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorInvalidNonConfig);
+            return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorInvalidNonConfig);
-            return {};
+
-        }
         // b. If resultDesc has a [[Writable]] field and resultDesc.[[Writable]] is false, then
         if (result_desc.writable.has_value() && !*result_desc.writable) {
             // i. If targetDesc.[[Writable]] is true, throw a TypeError exception.
-            if (*target_descriptor->writable) {
+            if (*target_descriptor->writable)
-                vm.throw_exception<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorNonConfigurableNonWritable);
+                return vm.throw_completion<TypeError>(global_object, ErrorType::ProxyGetOwnDescriptorNonConfigurableNonWritable);
-                return {};
-            }
         }
     }
 
     // 18. Return resultDesc.
-    return result_desc;
+    return { result_desc };
 }
 
 // 10.5.6 [[DefineOwnProperty]] ( P, Desc ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-defineownproperty-p-desc
@@ -384,9 +369,7 @@ bool ProxyObject::internal_define_own_property(PropertyName const& property_name
         return false;
 
     // 11. Let targetDesc be ? target.[[GetOwnProperty]](P).
-    auto target_descriptor = m_target.internal_get_own_property(property_name);
+    auto target_descriptor = TRY_OR_DISCARD(m_target.internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 12. Let extensibleTarget be ? IsExtensible(target).
     auto extensible_target = m_target.is_extensible();
@@ -476,9 +459,7 @@ bool ProxyObject::internal_has_property(PropertyName const& property_name) const
     // 9. If booleanTrapResult is false, then
     if (!trap_result) {
         // a. Let targetDesc be ? target.[[GetOwnProperty]](P).
-        auto target_descriptor = m_target.internal_get_own_property(property_name);
+        auto target_descriptor = TRY_OR_DISCARD(m_target.internal_get_own_property(property_name));
-        if (vm.exception())
-            return {};
 
         // b. If targetDesc is not undefined, then
         if (target_descriptor.has_value()) {
@@ -558,9 +539,7 @@ Value ProxyObject::internal_get(PropertyName const& property_name, Value receive
     auto trap_result = TRY_OR_DISCARD(vm.call(*trap, &m_handler, &m_target, property_name_to_value(vm, property_name), receiver));
 
     // 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
-    auto target_descriptor = m_target.internal_get_own_property(property_name);
+    auto target_descriptor = TRY_OR_DISCARD(m_target.internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 10. If targetDesc is not undefined and targetDesc.[[Configurable]] is false, then
     if (target_descriptor.has_value() && !*target_descriptor->configurable) {
@@ -626,9 +605,7 @@ bool ProxyObject::internal_set(PropertyName const& property_name, Value value, V
         return false;
 
     // 10. Let targetDesc be ? target.[[GetOwnProperty]](P).
-    auto target_descriptor = m_target.internal_get_own_property(property_name);
+    auto target_descriptor = TRY_OR_DISCARD(m_target.internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 11. If targetDesc is not undefined and targetDesc.[[Configurable]] is false, then
     if (target_descriptor.has_value() && !*target_descriptor->configurable) {
@@ -691,9 +668,7 @@ bool ProxyObject::internal_delete(PropertyName const& property_name)
         return false;
 
     // 10. Let targetDesc be ? target.[[GetOwnProperty]](P).
-    auto target_descriptor = m_target.internal_get_own_property(property_name);
+    auto target_descriptor = TRY_OR_DISCARD(m_target.internal_get_own_property(property_name));
-    if (vm.exception())
-        return {};
 
     // 11. If targetDesc is undefined, return true.
     if (!target_descriptor.has_value())
@@ -799,7 +774,10 @@ MarkedValueList ProxyObject::internal_own_property_keys() const
     // 16. For each element key of targetKeys, do
     for (auto& key : target_keys) {
         // a. Let desc be ? target.[[GetOwnProperty]](key).
-        auto descriptor = m_target.internal_get_own_property(PropertyName::from_value(global_object, key));
+        auto descriptor_or_error = m_target.internal_get_own_property(PropertyName::from_value(global_object, key));
+        if (descriptor_or_error.is_error())
+            return MarkedValueList { heap() };
+        auto descriptor = descriptor_or_error.release_value();
 
         // b. If desc is not undefined and desc.[[Configurable]] is false, then
         if (descriptor.has_value() && !*descriptor->configurable) {

Userland/Libraries/LibJS/Runtime/ProxyObject.h

@@ -39,7 +39,7 @@ public:
     virtual ThrowCompletionOr<bool> internal_set_prototype_of(Object* prototype) override;
     virtual ThrowCompletionOr<bool> internal_is_extensible() const override;
     virtual ThrowCompletionOr<bool> internal_prevent_extensions() override;
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const&) const override;
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const&) const override;
     virtual bool internal_define_own_property(PropertyName const&, PropertyDescriptor const&) override;
     virtual bool internal_has_property(PropertyName const&) const override;
     virtual Value internal_get(PropertyName const&, Value receiver) const override;

Userland/Libraries/LibJS/Runtime/ReflectObject.cpp

@@ -192,9 +192,7 @@ JS_DEFINE_NATIVE_FUNCTION(ReflectObject::get_own_property_descriptor)
         return {};
 
     // 3. Let desc be ? target.[[GetOwnProperty]](key).
-    auto descriptor = target.as_object().internal_get_own_property(key);
+    auto descriptor = TRY_OR_DISCARD(target.as_object().internal_get_own_property(key));
-    if (vm.exception())
-        return {};
 
     // 4. Return FromPropertyDescriptor(desc).
     return from_property_descriptor(global_object, descriptor);

Userland/Libraries/LibJS/Runtime/StringObject.cpp

@@ -92,12 +92,12 @@ static Optional<PropertyDescriptor> string_get_own_property(GlobalObject& global
 }
 
 // 10.4.3.1 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-string-exotic-objects-getownproperty-p
-Optional<PropertyDescriptor> StringObject::internal_get_own_property(PropertyName const& property_name) const
+ThrowCompletionOr<Optional<PropertyDescriptor>> StringObject::internal_get_own_property(PropertyName const& property_name) const
 {
     // Assert: IsPropertyKey(P) is true.
 
     // 2. Let desc be OrdinaryGetOwnProperty(S, P).
-    auto descriptor = Object::internal_get_own_property(property_name);
+    auto descriptor = Object::internal_get_own_property(property_name).release_value();
 
     // 3. If desc is not undefined, return desc.
     if (descriptor.has_value())

Userland/Libraries/LibJS/Runtime/StringObject.h

@@ -27,7 +27,7 @@ public:
     }
 
 private:
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const&) const override;
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const&) const override;
     virtual bool internal_define_own_property(PropertyName const&, PropertyDescriptor const&) override;
     virtual MarkedValueList internal_own_property_keys() const override;
 

Userland/Libraries/LibJS/Runtime/TypedArray.h

@@ -188,7 +188,7 @@ class TypedArray : public TypedArrayBase {
 
 public:
     // 10.4.5.1 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-getownproperty-p
-    virtual Optional<PropertyDescriptor> internal_get_own_property(PropertyName const& property_name) const override
+    virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyName const& property_name) const override
     {
         // 1. Assert: IsPropertyKey(P) is true.
         VERIFY(property_name.is_valid());
@@ -211,15 +211,15 @@ public:
 
                 // ii. If value is undefined, return undefined.
                 if (value.is_undefined())
-                    return {};
+                    return Optional<PropertyDescriptor> {};
 
                 // iii. Return the PropertyDescriptor { [[Value]]: value, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: true }.
-                return PropertyDescriptor {
+                return { PropertyDescriptor {
                     .value = value,
                     .writable = true,
                     .enumerable = true,
                     .configurable = true,
-                };
+                } };
             }
         }
 

Userland/Services/WebContent/ConsoleGlobalObject.cpp

@@ -57,9 +57,9 @@ JS::ThrowCompletionOr<bool> ConsoleGlobalObject::internal_prevent_extensions()
     return m_window_object->internal_prevent_extensions();
 }
 
-Optional<JS::PropertyDescriptor> ConsoleGlobalObject::internal_get_own_property(JS::PropertyName const& property_name) const
+JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> ConsoleGlobalObject::internal_get_own_property(JS::PropertyName const& property_name) const
 {
-    if (auto result = m_window_object->internal_get_own_property(property_name); result.has_value())
+    if (auto result = TRY(m_window_object->internal_get_own_property(property_name)); result.has_value())
         return result;
 
     return Base::internal_get_own_property(property_name);

Userland/Services/WebContent/ConsoleGlobalObject.h

@@ -27,7 +27,7 @@ public:
     virtual JS::ThrowCompletionOr<bool> internal_set_prototype_of(Object* prototype) override;
     virtual JS::ThrowCompletionOr<bool> internal_is_extensible() const override;
     virtual JS::ThrowCompletionOr<bool> internal_prevent_extensions() override;
-    virtual Optional<JS::PropertyDescriptor> internal_get_own_property(JS::PropertyName const& name) const override;
+    virtual JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> internal_get_own_property(JS::PropertyName const& name) const override;
     virtual bool internal_define_own_property(JS::PropertyName const& name, JS::PropertyDescriptor const& descriptor) override;
     virtual bool internal_has_property(JS::PropertyName const& name) const override;
     virtual JS::Value internal_get(JS::PropertyName const&, JS::Value) const override;