Merge pull request godotengine#86999 from AThousandShips/init_note

Improve error message when a GDScript instance fails to be constructed

Author: akien-mga

modules/gdscript/gdscript.cpp

@@ -162,13 +162,14 @@ GDScriptInstance *GDScript::_create_instance(const Variant **p_args, int p_argco
 
 	_super_implicit_constructor(this, instance, r_error);
 	if (r_error.error != Callable::CallError::CALL_OK) {
+		String error_text = Variant::get_call_error_text(instance->owner, "@implicit_new", nullptr, 0, r_error);
 		instance->script = Ref<GDScript>();
 		instance->owner->set_script_instance(nullptr);
 		{
 			MutexLock lock(GDScriptLanguage::singleton->mutex);
 			instances.erase(p_owner);
 		}
-		ERR_FAIL_V_MSG(nullptr, "Error constructing a GDScriptInstance.");
+		ERR_FAIL_V_MSG(nullptr, "Error constructing a GDScriptInstance: " + error_text);
 	}
 
 	if (p_argcount < 0) {
@@ -179,13 +180,14 @@ GDScriptInstance *GDScript::_create_instance(const Variant **p_args, int p_argco
 	if (initializer != nullptr) {
 		initializer->call(instance, p_args, p_argcount, r_error);
 		if (r_error.error != Callable::CallError::CALL_OK) {
+			String error_text = Variant::get_call_error_text(instance->owner, "_init", p_args, p_argcount, r_error);
 			instance->script = Ref<GDScript>();
 			instance->owner->set_script_instance(nullptr);
 			{
 				MutexLock lock(GDScriptLanguage::singleton->mutex);
 				instances.erase(p_owner);
 			}
-			ERR_FAIL_V_MSG(nullptr, "Error constructing a GDScriptInstance.");
+			ERR_FAIL_V_MSG(nullptr, "Error constructing a GDScriptInstance: " + error_text);
 		}
 	}
 	//@TODO make thread safe