[Fix]Close transceiver before closing the PeerConnection (#538)

Sources/StreamVideo/WebRTC/v2/PeerConnection/StreamRTCPeerConnection.swift

@@ -189,6 +189,11 @@ final class StreamRTCPeerConnection: StreamRTCPeerConnectionProtocol, @unchecked
 
     /// Closes the peer connection.
     func close() {
+        /// It's very important to close any transceivers **before** we close the connection, to make
+        /// sure that access to `RTCVideoTrack` properties, will be handled correctly. Otherwise
+        /// if we try to access any property/method on a `RTCVideoTrack` instance whose
+        /// peerConnection has closed, we will get blocked on the Main Thread.
+        source.transceivers.forEach { $0.stopInternal() }
         source.close()
     }
 }