Change exit code on worker's timeout as this is the expected termination.

Author: robertodauria

src/ndt7.js

@@ -149,7 +149,10 @@
       });
 
       // If the worker takes 10 seconds, kill it and return an error code.
-      setTimeout(() => worker.resolve(2), 10000);
+      // Most clients take longer than 10 seconds to complete the upload and
+      // finish sending the buffer's content, sometimes hitting the socket's
+      // timeout of 15 seconds. This makes sure uploads terminate on time.
+      setTimeout(() => worker.resolve(0), 10000);
 
       // This is how the worker communicates back to the main thread of
       // execution.  The MsgTpe of `ev` determines which callback the message