add socket validation

src/Xash3D/Master.php

@@ -19,11 +19,14 @@ class Master
             $port
         );
 
+        if ($this->_socket)
+        {
             stream_set_timeout(
                 $this->_socket,
                 $timeout
             );
         }
+    }
 
     public function __destruct()
     {