Show "Failed to join room" instead of error

Issue #140.

src/assets/translations/en.json

@@ -136,7 +136,8 @@
     "join": "Join room",
     "join_guest": "Join as guest",
     "status_logging_in": "Logging in...",
-    "status_joining": "Joining room..."
+    "status_joining": "Joining room...",
+    "join_failed": "Failed to join room."
   },
   "invite": {
     "title": "Add Friends",

src/components/Join.vue

@@ -399,7 +399,7 @@ export default {
           // TODO - handle error
           console.log("Failed to join room", err);
           this.loading = false;
-          this.loadingMessage = err.toString();
+          this.loadingMessage = this.$t("join.join_failed");
         });
     },