This was found by fuzzing, it causes a lot of weird error output, then crashes trying to close an invalid device object:

(Note, it only Repros with -f, it doesn't seem to work interactively)

$ cat current.ps
/Foobar
false
{ .startnewjob } stopped {} if
/Foobar exch def Foobar
{}
{ .unstoppederrorhandler } stopped {} if
.uninstallpagedevice
{ .runstringbegin } stopped {} if
grestoreall
{ wtranslation } stopped {} if
currentscreen
{ devforall } stopped {} if
.pdfcvsall
{ quit } stopped {} if
./gs -q -sDEVICE=ppmraw -dSAFER -f current.ps
Unrecoverable error: --nostringval-- in Foobar
<lots of error output>
Segmentation fault