Fig should not preserve empty functions.

[elas7]

Sanity checks

• [X] I have searched github.com/withfig/fig/issues and there are no duplicates of my feature

Feature Details

If one accidentally clicks on "new function" without filling out anything in the Fig UI, Fig saves it as an empty function. This can cause obscure bugs - at least when using the Fish shell (example).

I think Fig should remove functions if they are clearly empty.