Merge pull request godotengine#92216 from dsnopek/runtime-classes-err-print-once

Don't use `ERR_PRINT_ONCE()` for runtime class error because it will hide errors

Author: akien-mga

core/object/class_db.cpp

@@ -522,7 +522,7 @@ Object *ClassDB::_instantiate_internal(const StringName &p_class, bool p_require
 #ifdef TOOLS_ENABLED
 		if (!p_require_real_class && ti->is_runtime && Engine::get_singleton()->is_editor_hint()) {
 			if (!ti->inherits_ptr || !ti->inherits_ptr->creation_func) {
-				ERR_PRINT_ONCE(vformat("Cannot make a placeholder instance of runtime class %s because its parent cannot be constructed.", ti->name));
+				ERR_PRINT(vformat("Cannot make a placeholder instance of runtime class %s because its parent cannot be constructed.", ti->name));
 			} else {
 				ObjectGDExtension *extension = get_placeholder_extension(ti->name);
 				return (Object *)extension->create_instance(extension->class_userdata);