fix notification "Key null invalidated" on cancel device pairing

index.js

@@ -286,14 +286,16 @@ class PairDropServer {
     }
 
     _onPairDeviceCancel(sender) {
-        if (sender.roomKey) {
-            this._removeRoomKey(sender.roomKey);
+        const roomKey = sender.roomKey
+
+        if (!roomKey) return;
+
+        this._removeRoomKey(roomKey);
         this._send(sender, {
             type: 'pair-device-canceled',
-                roomKey: sender.roomKey,
+            roomKey: roomKey,
         });
     }
-    }
 
     _onRegenerateRoomSecret(sender, message) {
         const oldRoomSecret = message.roomSecret;