Preview not working if fish is not the default shell

[svenihoney]

If fish is not the default user shell, the preview command fails due to a command not found error:

/run/current-system/sw/bin/bash: line 1: _fifc_action: Command not found.

To Reproduce
Steps to reproduce the behavior:

• Set default shell to bash
• Run fish from bash with fifc installed
• Trigger a completion with tab

Expected behavior
Preview should be working independently of the selected default shell.

Screenshots

System (please complete the following information):

• fish version 3.7.1
• Distribution NixOS unstable

** Possible workaround/fix:**

--preview 'fish -c \"_fifc_action preview {} {q}\"' \