[luatex] luatex panics if an obj is written twice

[Ulrike Fischer]

I inadvertently tried to write the same object twice:

blbl
 \pdfextension obj reserveobjnum
 \edef\mynum{\pdffeedback lastobj}
  \pdfextension obj useobjnum \mynum {something}
  \pdfextension obj useobjnum \mynum {something}
\bye

and then luatex panicked:

(./test-utf8.texPANIC: unprotected error in call to Lua API (object
in use)

A similar error in pdflatex gives only a warning:
pdfTeX warning (\pdfobj): invalid object number being ignored

Can one avoid the PANIC crash?
And how can I test if the object number is valid before trying to
write the object?


-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/