message: style(background): use generics
diff: @@ -42,10 +42,11 @@ function onInstalled ({ reason, previousVersion }: { reason: string, previousVer
  function onStartup (): void {
  // check update every month
  - Promise.all([storage.local.get('lastCheckUpdate'), storage.sync.get('config')])
  - .then(([r1, r2]) => {
  - const lastCheckUpdate = r1.lastCheckUpdate as number
  - const config = r2.config as AppConfig
  + Promise.all([
  + storage.local.get<{ lastCheckUpdate: number }>('lastCheckUpdate'),
  + storage.sync.get<{ config: AppConfig }>('config'),
  + ])
  + .then(([{ lastCheckUpdate }, { config }]) => {
  initMenus(config.contextMenus)
  initPdf(config.pdfSniff)
  const today = Date.now()
  