fix(fish): allow an arbitrary word before line number

[metiulekm]

The error message generated by fish --no-execute varies by locale. For instance:

$ cat test.fish
|
$ LANG=C fish --no-execute test.fish
test.fish (line 1): Expected a string, but found a pipe
|
^
warning: Error while reading file test.fish

$ LANG=pl_PL.UTF-8 fish --no-execute test.fish
test.fish (linia 1): Expected a string, but found a pipe
|
^
warning: Wystąpił błąd podczas odczytywania pliku test.fish

This means that hardcoding the word line into the errorformat is too strong. This commit replaces it with an arbitrary string not containing a space character (%[%^ ]%#).

Fixes #708.