try except in lilypond

[Noeck]

Hi,

is there something like try ... except in lilypond. What I want to
achieve is some failure tolerance in ly files. I want to load some fonts
or include files and if they don't exist, it should just be skipped
without stopping the compilation (perhaps a warning could be printed).

Is that possible? I think I remember that some 'if then else' syntax is
not available. This thing probably even less.

Best,
Joram