Bug 1646273 - Add a nullptr check in ns_socket_tcp before sending data, r=bwc

Differential Revision: https://phabricator.services.mozilla.com/D79950

media/mtransport/nr_socket_tcp.cpp

@@ -156,6 +156,10 @@ int NrTcpSocket::write(const void* aBuffer, size_t aCount, size_t* aWrote) {
     return R_FAILED;
   }
 
+  if (NS_WARN_IF(!mWebrtcTCPSocket)) {
+    return R_FAILED;
+  }
+
   *aWrote = aCount;
 
   if (aCount > 0) {