fix: Clear up knocking state on error.

Fixes a case where participant is not entering lobby when trying the second time after being rejected.

react/features/lobby/reducer.ts

@@ -60,7 +60,10 @@ ReducerRegistry.register<ILobbyState>('features/lobby', (state = DEFAULT_STATE,
             };
         }
 
-        return state;
+        return {
+            ...state,
+            knocking: false
+        };
     }
     case CONFERENCE_JOINED:
     case CONFERENCE_LEFT: