handle no sw registration gracefully

src/services/sw/sw.js

@@ -99,11 +99,13 @@ export async function initServiceWorker (store) {
 
 export async function showDesktopNotification (content) {
   const { active: sw } = await window.navigator.serviceWorker.getRegistration()
+  if (!sw) return console.error('No serviceworker found!')
   sw.postMessage({ type: 'desktopNotification', content })
 }
 
 export async function closeDesktopNotification ({ id }) {
   const { active: sw } = await window.navigator.serviceWorker.getRegistration()
+  if (!sw) return console.error('No serviceworker found!')
   if (id >= 0) {
     sw.postMessage({ type: 'desktopNotificationClose', content: { id } })
   } else {
@@ -113,6 +115,7 @@ export async function closeDesktopNotification ({ id }) {
 
 export async function updateFocus () {
   const { active: sw } = await window.navigator.serviceWorker.getRegistration()
+  if (!sw) return console.error('No serviceworker found!')
   sw.postMessage({ type: 'updateFocus' })
 }