🚀 go-pugleaf

My objective is to write a PostScript program that can run on a
machine, local or remote, that outputs a PDF file listing and giving
an example of the usable fonts. For these purposes I want Roman-type
fonts, so fonts with a non-zero /WMode are being ignored, as are those
the with a zero-width or zero-height bounding box of a "W".

The current code is at www.jdawiseman.com/papers/placemat/fonts_illustrated.ps
and it works as follows:
-- makes a list of fonts with (*) {cvn 255 string cvs} 255 string /
Font resourceforall;
-- sorts;
-- runs through fonts;
-- within which there is a 1 {} repeat construct so that {exit} is the
equivalent of the C continue statement;
-- invoke anything using fonts within a {} stopped construct;
-- if the stopped fails, or the above tests fail, don't show;
-- otherwise, still within {} stopped, show;
-- the {} stopped is surrounded by a mark ... cleartomark, to tidy
detritus left on stack by a failure somewhere, and, out of paranoia,
also a gsave ... grestore.

Work through the alphabetically-ordered fonts 0 to 877 on my computer,
a splendid multi-page PDF is produced. After which stack is empty,
graphics stack where it started, etc, Hurray!

But once it hits
   %%[ Error: Math1 cannot be embedded because of licensing
restrictions. ]%%
things get more interesting. Execution continues until the end. But
then, after my log outputs, so after PostScript execution completed,
Distiller Professional 8.1.2 (10/23/06) also says:
   Error %d: %%[ Error: PDF object referenced, never defined ]%%
   %%[ Error: undefined; OffendingCommand: distillsave; ErrorInfo:
Internal Distiller Error 4]%%
   %%[ Warning: PostScript error. No PDF file produced. ] %%

Please, what can I do to catch this error? Can fonts be tested for non-
embeddability? Is there anything else I can do? (Changing the PDF
standard doesn't seem to help.)