Update public/screenshare.js

public/screenshare.js

@@ -632,6 +632,11 @@ class ScreenShareManager {
       this.recognition.removeEventListener('end', this._handleRecognitionEnd);
       this.recognition = null;
     }
+
+    // Defensive cleanup of track/listener and retry state
+    this._videoTrack = null;
+    this._surfaceChangeListener = null;
+    this._retryCount = 0;
   }
 
   /**