it works with Zandronum?
Yes, with the caveat that you'll need to open up the doom_complete.pk3 file WadSmoosh generates, and delete the file "menudef.txt" there to fix the startup error. Zandronum doesn't support some of the menu scripting features GZDoom has.
although this sounds annoying, how do I do it? I didn't understand
The doom_complete.pk3 file is actually just a ZIP file with a different extension (suffix), and you can open it using whatever you normally use to inspect and edit the contents of ZIP files. Just inside it, you'll find a file called MENUDEF.TXT. Simply delete it, then try launching in Zandronum again.