Fix app loading failure handling

changelog/unreleased/default-extension

@@ -0,0 +1,6 @@
+Change: Configurable default extension
+
+We introduced a config option in the config.json file which allows to configure the default extension for ownCloud Web.
+Any of the configured extension ids can be chosen as default extension. If none is provided, we fall back to the files extension.
+
+https://github.com/owncloud/phoenix/pull/4382

changelog/unreleased/extension-loading

@@ -0,0 +1,6 @@
+Bugfix: Unavailable extensions causing route duplication
+
+There was an error in the extension loading handlers which caused routes to be loaded multiple times when extensions from the config.json were unavailable.
+We hardened the extension loading handlers to just skip those extensions.
+
+https://github.com/owncloud/phoenix/pull/4382

src/components/Avatar.vue

@@ -62,9 +62,9 @@ export default {
     }
   },
   computed: {
-    ...mapGetters(['getToken']),
+    ...mapGetters(['getToken', 'configuration']),
     enabled: function() {
-      return this.$root.config.enableAvatars || true
+      return this.configuration.enableAvatars || true
     }
   },
   watch: {
@@ -92,7 +92,7 @@ export default {
         return
       }
       const headers = new Headers()
-      const instance = this.$root.config.server || window.location.origin
+      const instance = this.configuration.server || window.location.origin
       const url = instance + '/remote.php/dav/avatars/' + this.userid + '/128.png'
       headers.append('Authorization', 'Bearer ' + this.getToken)
       headers.append('X-Requested-With', 'XMLHttpRequest')

src/components/Top-Bar.vue

@@ -32,7 +32,6 @@
 
 <script>
 import { mapGetters } from 'vuex'
-import pluginHelper from '../mixins/pluginHelper.js'
 import ApplicationsMenu from './ApplicationsMenu.vue'
 import UserMenu from './UserMenu.vue'
 import Notifications from './Notifications.vue'
@@ -45,7 +44,6 @@ export default {
     UserMenu,
     SearchBar
   },
-  mixins: [pluginHelper],
   props: {
     userId: {
       type: String,