LibJS: Implement the RequireObjectCoercible abstract operation

Throws an exception if the given value is nullish, returns it otherwise.
We can now gradually replace such manual checks with this function where
applicable.

This also has the advantage that the somewhat useless "ToObject on null
or undefined" will be replaced with "null cannot be converted to an
object" or "undefined cannot be converted to an object". :^)

Userland/Libraries/LibJS/Runtime/ErrorTypes.h

@@ -44,6 +44,7 @@
     M(JsonCircular, "Cannot stringify circular object")                                                                                 \
     M(JsonMalformed, "Malformed JSON string")                                                                                           \
     M(NegativeExponent, "Exponent must be positive")                                                                                    \
+    M(NonExtensibleDefine, "Cannot define property {} on non-extensible object")                                                        \
     M(NotA, "Not a {} object")                                                                                                          \
     M(NotAConstructor, "{} is not a constructor")                                                                                       \
     M(NotAFunction, "{} is not a function")                                                                                             \
@@ -52,7 +53,7 @@
     M(NotAnObject, "{} is not an object")                                                                                               \
     M(NotASymbol, "{} is not a symbol")                                                                                                 \
     M(NotIterable, "{} is not iterable")                                                                                                \
-    M(NonExtensibleDefine, "Cannot define property {} on non-extensible object")                                                        \
+    M(NotObjectCoercible, "{} cannot be converted to an object")                                                                        \
     M(NumberIncompatibleThis, "Number.prototype.{}() called with incompatible this target")                                             \
     M(ObjectDefinePropertyReturnedFalse, "Object's [[DefineProperty]] method returned false")                                           \
     M(ObjectFreezeFailed, "Could not freeze object")                                                                                    \

Userland/Libraries/LibJS/Runtime/Value.cpp

@@ -1390,4 +1390,16 @@ Object* species_constructor(GlobalObject& global_object, const Object& object, O
     vm.throw_exception<TypeError>(global_object, ErrorType::NotAConstructor, species.to_string_without_side_effects());
     return nullptr;
 }
+
+// 7.2.1 RequireObjectCoercible, https://tc39.es/ecma262/#sec-requireobjectcoercible
+Value require_object_coercible(GlobalObject& global_object, Value value)
+{
+    auto& vm = global_object.vm();
+    if (value.is_nullish()) {
+        vm.throw_exception<TypeError>(global_object, ErrorType::NotObjectCoercible, value.to_string_without_side_effects());
+        return {};
+    }
+    return value;
+}
+
 }

Userland/Libraries/LibJS/Runtime/Value.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -366,6 +367,7 @@ TriState abstract_relation(GlobalObject&, bool left_first, Value lhs, Value rhs)
 Function* get_method(GlobalObject& global_object, Value, const PropertyName&);
 size_t length_of_array_like(GlobalObject&, const Object&);
 Object* species_constructor(GlobalObject&, const Object&, Object& default_constructor);
+Value require_object_coercible(GlobalObject&, Value);
 
 }