fix(app): prevent focus issue by checking frame existence before handling dom-ready

src/main/app.ts

@@ -610,6 +610,10 @@ if (!gotTheLock) {
 
     // fix focus issue after dialog show on Windows.
     webContents.on('frame-created', (_, { frame }) => {
+      if (!frame) {
+        return
+      }
+
       frame.on('dom-ready', () => {
         frame.executeJavaScript(`if ('ctx' in window && ctx?.env?.isWindows) {
           window._FIX_ELECTRON_DIALOG_FOCUS ??= function () {