is-interactive | Check if stdout or stderr | Command Line Interface library

What happens here is that a component of your $PATH, $fish_user_paths or a line in /etc/paths looks like an option.

Most likely, this is wrong, and you should remove it.

E.g. try printf '%s\n' $fish_user_paths. If that tells you that one of the entries is "-gx", then you've set it incorrectly and need to use set -e fish_user_paths[number-of-that-entry] to correct it.

Since these are all common options to set, you've probably once done something like set fish_user_paths /something -gx, which adds a "-gx" component (set only reads options before the variable name).

This has been reported upstream at https://github.com/fish-shell/fish-shell/issues/5662, and future fish versions won't spew an error, but the existence of the offending component is most likely an error, so you still want to remove it.

Of course fish can handle nested if statements!

I believe the cause is that you are initializing PyEnv in the Fish shell environment but then calling PyEnv in the Bash shell environment (via your Bash script). To solve this problem, you could try either of the following potential solutions:

1. Initialize PyEnv in your Bash environment (in addition to your Fish environment)
2. Write your script in Fish instead of Bash

Since PyEnv seems so have better support for Bash than Fish, let's focus on option #1. Step 3 of the PyEnv installation guide suggests the following command for adding PyEnv initialization to your ~/.bash_profile:

I can't figure out why your code doesn't work. Maybe it's just that it's not meant to be used this way. The only workaround I found is the one below, but I'm pretty sure something better can be done.