message: Added window.matchMedia to App.tsx
diff: @@ -66,6 +66,10 @@ const App: FC<{}> = () => {
  backstageTheme = BackstageThemeDark;
  break;
  default:
  + if (!window.matchMedia) {
  + backstageTheme = BackstageThemeLight;
  + break;
  + }
  backstageTheme = window.matchMedia('(prefers-color-scheme: dark)').matches
  ? BackstageThemeDark
  : BackstageThemeLight;
  