change next card logic for kanji

lib/screens/practise/kanji.dart

@@ -104,9 +104,11 @@ class _KanjiPageState extends State<KanjiPage> {
                 setState(() => isPressed = !isPressed);
               },
               onNextCard: () => setState(() {
+                if (isPressed) {
                   controller.clear();
-                isPressed = false;
                   widget.onNextCard();
+                }
+                setState(() => isPressed = !isPressed);
               }),
               onPreviousCard: () => setState(() {
                 controller.clear();