Check socket handle for disconnect

If the remote server disconnects, the read call will block, meaning the thread will not end when expected. Once the socket is shutdown, the call will return with an invalid handle, which can be caught and returned correctly

Source/EphysSocket.cpp

@@ -264,6 +264,12 @@ void EphysSocket::runBufferThread()
 
         if (rc == -1)
         {
+            if (socket->getRawSocketHandle() == -1)
+            {
+                CoreServices::sendStatusMessage("Ephys Socket: Socket handle is no longer valid.");
+                return;
+            }
+
             CoreServices::sendStatusMessage("Ephys Socket: Data shape mismatch");
             error_flag = true;
             return;