Debugging the msvc build of gxps circa r9883, I discovered a segfault in pjl_check_font_path(), which was assuming gs_enumerate_file_next would fail if passed the return value of gs_enumerate_files_init(), even if the later returned NULL to indicate failure. This was fixed in r9884, but I think it's worth checking the arguments in the implementations as well. The extra conditional isn't expensive relative to talking to a filesystem, and we'll gain much better error recovery elsewhere.
Closing, it isn't exactly clear what is being requested in the initial description.