fix build warnings

src/components/panel_loading/panel_loading.vue

@@ -18,6 +18,8 @@ import { faCircleNotch } from '@fortawesome/free-solid-svg-icons'
 library.add(
   faCircleNotch
 )
+
+export default {}
 </script>
 
 <style lang="scss">

src/components/settings_modal/tabs/theme_tab/preview.vue

@@ -126,6 +126,8 @@ library.add(
   faRetweet,
   faReply
 )
+
+export default {}
 </script>
 
 <style lang="scss">