Make sure important errors are always shown to the user

Summary:
This diff makes sure that important errors are always shown to the user, such as an xcode version mismatch.

Also made some small styling improvements

Reviewed By: jknoxville

Differential Revision: D19660337

fbshipit-source-id: 24dfb4d98bfdd1666164403f87b6a4e1dc915ddb

src/utils/argvUtils.tsx

@@ -7,7 +7,6 @@
  * @format
  */
 
-import electron from 'electron';
 import isProduction from './isProduction';
 import processConfig from './processConfig';