[NTG-context] die if a module is missing

I was recently debugging some presentation that I was working on in ConTeXt and found, to my surprise, that the problem was that I was using \usemodule[blah-blah] but there was no such module called blah-blah. The output does indeed say that there was no such module, but I didn't see that. Is there a way to set up modules so that, if a module isn't found, an error is generated and the TeX run is stopped? I would have discovered the source of my problem more quickly had I been able to set things up in that way. Thanks, Jesse -- Jesse Alama (alama@stanford.edu)