code: func (a *App) RunAndExitOnError() {
  	if err := a.Run(os.Args); err != nil {
  		fmt.Fprintln(a.errWriter(), err)
  		OsExiter(1)
  	}
  }
docs: // RunAndExitOnError calls .Run() and exits non-zero if an error was returned
  //
  // Deprecated: instead you should return an error that fulfills cli.ExitCoder
  // to cli.App.Run. This will cause the application to exit with the given eror
  // code in the cli.ExitCoder