[Monetdb-developers] [PATCH] Mx Io.c more specific errors

Hi devs, I ran into a problem with Mx, where IoWriteToFile seemed to have a problem but didn't tell exactly what. With the attached patch, I was able to figure out what the problem was. I don't like to commit it, as the Mx code is completely unknown to me. Also, I have no ideas on the effects on this highly portable piece of code on Windows. If someone considers it useful to commit, please do.