Fix #2826. (#2827)

HMCL/src/main/java/org/jackhuang/hmcl/ui/FXUtils.java

@@ -907,8 +907,10 @@ public final class FXUtils {
         content.putString(text);
         Clipboard.getSystemClipboard().setContent(content);
 
+        if (!Controllers.isStopped()) {
             Controllers.showToast(i18n("message.copied"));
         }
+    }
 
     public static List<Node> parseSegment(String segment, Consumer<String> hyperlinkAction) {
         if (segment.indexOf('<') < 0)