Just as if (and unless) can be used as a modifier, else could be used as a modifier. That would be clear indication of intent.

Ahhh, the sweet smell of MUMPS:

  OPEN 51:("foobar.txt":"W"):0
  ELSE  GOTO error
[download]

(Note the significant white space)

Or, slightly shorter:

  O 51:("foobar.txt":"W"):0 E  G error
[download]

I can live with both, but open ... or die is shorter than open ... else die, and it's not that hard to understand.

Alexander