Merge pull request #70030 from KoBeWi/why_is_tween

Improve empty Tween error message

scene/animation/tween.cpp

@@ -280,7 +280,16 @@ bool Tween::step(double p_delta) {
 	}
 
 	if (!started) {
-		ERR_FAIL_COND_V_MSG(tweeners.is_empty(), false, "Tween started, but has no Tweeners.");
+		if (tweeners.is_empty()) {
+			String tween_id;
+			Node *node = get_bound_node();
+			if (node) {
+				tween_id = vformat("Tween (bound to %s)", node->is_inside_tree() ? (String)node->get_path() : (String)node->get_name());
+			} else {
+				tween_id = to_string();
+			}
+			ERR_FAIL_V_MSG(false, tween_id + ": started with no Tweeners.");
+		}
 		current_step = 0;
 		loops_done = 0;
 		total_time = 0;
@@ -393,6 +402,15 @@ Variant Tween::interpolate_variant(Variant p_initial_val, Variant p_delta_val, d
 	return ret;
 }
 
+String Tween::to_string() {
+	String ret = Object::to_string();
+	Node *node = get_bound_node();
+	if (node) {
+		ret += vformat(" (bound to %s)", node->get_name());
+	}
+	return ret;
+}
+
 void Tween::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("tween_property", "object", "property", "final_val", "duration"), &Tween::tween_property);
 	ClassDB::bind_method(D_METHOD("tween_interval", "time"), &Tween::tween_interval);

scene/animation/tween.h

@@ -130,6 +130,8 @@ protected:
 	static void _bind_methods();
 
 public:
+	virtual String to_string() override;
+
 	Ref<PropertyTweener> tween_property(Object *p_target, NodePath p_property, Variant p_to, double p_duration);
 	Ref<IntervalTweener> tween_interval(double p_time);
 	Ref<CallbackTweener> tween_callback(Callable p_callback);