don't push the stashes if there isn't any
don't push the stashes if there isn't any

If you did a `git fire` in a repo without any stash you would get this error:
```
fatal: ambiguous argument 'stash': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
```

qw3rtman/git-fire