fix(collector): unhandled unlink error event

Author: gergelyke

lib/collector.js

@@ -248,7 +248,9 @@ Collector.prototype._send = function (logFile) {
         debug(err);
       }
 
-      fs.unlink(logFile);
+      // do nothing if file cannot be removed
+      // mostl likely it is because it was never created in the first place
+      fs.unlink(logFile, function() {});
     });
 
   });