blocked webpack dev server and no such file or directory error

[pinggi]

The plugin has some issues:

1. when the remote app url is undefined, the plugin blocks webpack dev server indefinitely
2. if there's a path in the remoteFileName, the plugin is not able to save the file due to ENOENT

new WebpackRemoteTypesPlugin({
  remotes: {
    'app': undefined                  <-- `undefined` value blocks webpack dev server indefinitely 
  },
  outputDir: 'types',
  remoteFileName: 'types/dts.tgz'     <-- a path in `remoteFileName` causes "Error: ENOENT: no such file or directory"
}),

[ruanyl]

Thanks for reporting, I'll take a look. PR is welcome :)