Add kanji page

lib/screens/misc/error.dart

@@ -0,0 +1,15 @@
+import 'package:flutter/material.dart';
+
+class ErrorScreen extends StatelessWidget {
+  const ErrorScreen({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return const Center(
+      child: Icon(
+        Icons.error,
+        color: Colors.red,
+      ),
+    );
+  }
+}