Fix crash when playing Tween right after finishing

(cherry picked from commit 1a462bc84e095125661efb5a0254f36e73197cd9)

scene/animation/scene_tree_tween.cpp

@@ -304,6 +304,7 @@ bool SceneTreeTween::step(float p_delta) {
 					running = false;
 					dead = true;
 					emit_signal(SceneStringNames::get_singleton()->finished);
+					break;
 				} else {
 					emit_signal(SceneStringNames::get_singleton()->loop_finished, loops_done);
 					current_step = 0;