Fix 403 error on invited room chat page

Don't try to fetch room members while user is only invited or has left
the room.

TODO.md

@@ -23,6 +23,9 @@
 
 ## Issues
 
+- Show a proper error when accepting a room invite that has expired or
+  the room doesn't exist anymore (`MatrixNotFound`)
+
 - Replying to one of our own message that's currently only a local echo
   results in a reply to an empty ID
 

src/gui/Pages/Chat/ChatPage.qml

@@ -29,7 +29,7 @@ HColumnPage {
 
     Timer {
         interval: 200
-        running: true
+        running: ! chat.roomInfo.inviter_id && ! chat.roomInfo.left
         onTriggered: loadMembersFuture = py.callClientCoro(
             chat.userId,
             "load_all_room_members",