Fix the handling of a nil path within doom/delete-this-file.
If path is nil (e.g. called interactively when buffer is not visiting a
file), avoid calling abbreviate-file-name on nil, otherwise an error
will be signaled:
(wrong-type-argument stringp nil)
Additionally, fix the subsequent path checks. These were treating two
distinct scenarios as a "Buffer is not visiting any file" user-error:
- nil path
- non-existent path
- Only the first should result in that error. The second should proceed
to the next path check (which was previously unreachable), to signal
the appropriate error, "File doesn't exist: %s".
850907ed9a