Change int.Parse to int.TryParse

Prevent application crash by bad string passing to int.Parse by using int.TryParse instead.

goesrecv-monitor/Stats.cs

@@ -236,7 +236,7 @@ static void DecoderLoop()
 
                         if (rsStr != "-1")
                         {
-                            rsErr += int.Parse(rsStr);
+                            int.TryParse(rsStr, out rsErr);
                         }
                     }
                 }