Fix hitting RET on some text in compilation-mode

* lisp/progmodes/compile.el (compilation-next-error-function):
Don't bug out with an incomprehensible error message on "make[2]:"
texts (bug#5316).
(compilation-find-file): Protect against there being no file name.
1 job for master in 90 minutes and 1 second (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #3779
test-all

01:30:01

 
Name Stage Failure
failed
test-all Test The script exceeded the maximum execution time set for the job
  GEN      lisp/eshell/eshell-tests.log
ELC lisp/faces-tests.elc
GEN lisp/faces-tests.log
ELC lisp/ffap-tests.elc
GEN lisp/ffap-tests.log
ELC lisp/filenotify-tests.elc
GEN lisp/filenotify-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-d0b76032 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds