ui: handle WebSocket 403 unauthorized errors properly

When WebSocket connection fails due to 403 unauthorized status from server,
browser WebSocket API cannot distinguish HTTP status codes and only fires
a generic 'error' event. Redirect to /connect/:devid HTTP endpoint so that
browser can properly capture and handle the 403 status code response.

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>

ui/src/views/Rtty.vue

@@ -267,7 +267,12 @@ export default {
       }
     })
 
-    socket.addEventListener('error', () => this.closed())
+    socket.addEventListener('error', () => {
+      let href = `/connect/${this.devid}`
+      if (group)
+        href += `?group=${group}`
+      window.location.href = href
+    })
 
     socket.addEventListener('message', ev => {
       const data = ev.data