Fix: Early out from _forgit_stash_push when no files can be stashed

[sandr01d]

Check list

• [X] I have performed a self-review of my code
• [ ] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

Description

Previously when using gsp without any local changes, an empty file picker would open. Check if any files can be stashed and show a message instead when this isn't the case. Fixes #369

Type of change

• [X] Bug fix
• [ ] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [X] bash
  • [X] zsh
  • [ ] fish
• OS
  • [X] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Others:

[carlfriedrich]

Why not simply use fzf's --exit-0 argument for this?

[sandr01d]

Why not simply use fzf's --exit-0 argument for this?

@carlfriedrich wasn't aware this exists, thanks! Updated accordingly.

[sandr01d]

@carlfriedrich could you let me know if the change works like this for you?