Please check if zsh is available before installing

[tacone]

I forgot to install zsh and got this:

/usr/bin/env: zsh: No such file or directory

A preemptive check may be useful

[mcornella]

That's a good enough description of the problem already. In a near future we'll improve the install script and add a better message, but it works for the time being.
Thank you for your attention, we'll close the issue ✨