message: style(helpers): fix typing
diff: import { AppConfig, appConfigFactory } from '@/app-config'
  -import { StorageListenerCb, StorageChange } from '@/_helpers/browser-api'
  +import { StorageListenerCb } from '@/_helpers/browser-api'
  // import { map } from 'rxjs/operators'
  // import { Observable, fromEventPattern, of, concat } from 'rxjs'
  import { Observable } from 'rxjs/Observable'
  