Fix #4934: 返回页面时可能卡进空白页面 (#5305)

Author: CiiLu

HMCL/src/main/java/org/jackhuang/hmcl/ui/animation/TransitionPane.java

@@ -82,7 +82,9 @@ public void setContent(Node newView, AnimationProducer transition,
                     duration, interpolator);
             newAnimation.setOnFinished(e -> {
                 setMouseTransparent(false);
-                getChildren().remove(previousNode);
+                if (previousNode != currentNode) {
+                    getChildren().remove(previousNode);
+                }
 
                 if (cacheHint != null) {
                     newView.setCache(false);