Add eassert check for bad default face

* src/xdisp.c (append_space_for_newline): Add an eassert check
that default_face is not null, by calling FACE_FROM_ID instead of
FACE_FROM_ID_OR_NULL.  Initialize a local only if needed.
1 job for master in 60 minutes and 21 seconds (queued for 2 seconds)
Status Job ID Name Coverage
failed #4335


Name Stage Failure
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:319: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1