Fix authorization header when no access token

app/javascript/gabsocial/service_worker/web_push_notifications.js

@@ -40,12 +40,13 @@ const notify = options =>
 const fetchFromApi = (path, method, accessToken) => {
   const url = (new URL(path, self.location)).href;
 
+  let headers = {
+    'Authorization': `Bearer ${accessToken}`,
+    'Content-Type': 'application/json',
+  }
+  if (!accessToken) { delete headers['Authorization'] }
   return fetch(url, {
-    headers: {
-      'Authorization': `Bearer ${accessToken}`,
-      'Content-Type': 'application/json',
-    },
-
+    headers: headers,
     method: method,
     credentials: 'include',
   }).then(res => {