Fix editor on open

lib/view/page/editor.dart

@@ -29,7 +29,7 @@ class _EditorPageState extends State<EditorPage> with AfterLayoutMixin {
   late CodeController _controller;
   late final _focusNode = FocusNode();
   final _setting = locator<SettingStore>();
-  late Map<String, TextStyle> _codeTheme;
+  Map<String, TextStyle>? _codeTheme;
   late S _s;
   late String? _langCode;
 
@@ -41,13 +41,15 @@ class _EditorPageState extends State<EditorPage> with AfterLayoutMixin {
       language: suffix2HighlightMap[_langCode],
     );
 
+    WidgetsBinding.instance.addPostFrameCallback((Duration duration) async {
       if (isDarkMode(context)) {
         _codeTheme = themeMap[_setting.editorDarkTheme.fetch()] ?? monokaiTheme;
       } else {
         _codeTheme = themeMap[_setting.editorTheme.fetch()] ?? a11yLightTheme;
       }
-
       _focusNode.requestFocus();
+      setState(() {});
+    });
   }
 
   @override
@@ -66,7 +68,12 @@ class _EditorPageState extends State<EditorPage> with AfterLayoutMixin {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      backgroundColor: _codeTheme['root']!.backgroundColor,
+      backgroundColor: () {
+        if (_codeTheme != null) {
+          return _codeTheme!['root']!.backgroundColor;
+        }
+        return null;
+      }(),
       appBar: AppBar(
         centerTitle: true,
         title: TwoLineText(up: getFileName(widget.path) ?? '', down: _s.editor),
@@ -89,9 +96,14 @@ class _EditorPageState extends State<EditorPage> with AfterLayoutMixin {
           )
         ],
       ),
-      body: SingleChildScrollView(
+      body: Visibility(
+        visible: (_codeTheme != null),
+        replacement: const Center(
+          child: CircularProgressIndicator(),
+        ),
+        child: SingleChildScrollView(
           child: CodeTheme(
-          data: CodeThemeData(styles: _codeTheme),
+            data: CodeThemeData(styles: _codeTheme ?? (isDarkMode(context) ? monokaiTheme : a11yLightTheme)),
             child: CodeField(
               focusNode: _focusNode,
               controller: _controller,
@@ -102,6 +114,7 @@ class _EditorPageState extends State<EditorPage> with AfterLayoutMixin {
             ),
           ),
         ),
+      ),
       floatingActionButton: FloatingActionButton(
         child: const Icon(Icons.done),
         onPressed: () {