LibJS: Convert internal_get_prototype_of() to ThrowCompletionOr

Author: https://github.com/linusg
Commit: 5148150e1c
Pull-request: https://github.com/SerenityOS/serenity/pull/10266
Reviewed-by: https://github.com/IdanHo ✅

Userland/Libraries/LibJS/AST.cpp

@@ -580,9 +580,7 @@ Value ForInStatement::execute(Interpreter& interpreter, GlobalObject& global_obj
                 }
             }
         }
-        object = object->internal_get_prototype_of();
-        if (interpreter.exception())
-            return {};
+        object = TRY_OR_DISCARD(object->internal_get_prototype_of());
     }
     return last_value;
 }