fix isDev

public/electron.js

@@ -255,4 +255,4 @@ function focusWindow() {
   }
 }
 
-module.exports = { focusWindow };
+module.exports = { focusWindow, isDev };

src/isDev.js

@@ -1 +1,3 @@
-export default true; // todo
+const { isDev } = window.require('@electron/remote').require('./electron');
+
+export default isDev;