z: Installation with fin throws error for requiring `debug`

Here’s the log:

$ fin z
fin SAYS Installing 1 plugin
         ✔  z                       https://github.com/fishery/z
fish: Unknown command 'debug'
~/.config/fish/conf.d/z.fish (line 18): debug "$Z_CMD $ZO_CMD"
                                        ^
from sourcing file ~/.config/fish/conf.d/z.fish
    called on line 576 of file ~/.config/fish/functions/fin.fish

in function '__fin_plugin_enable'
    called on line 360 of file ~/.config/fish/functions/fin.fish
    with parameter list '/Users/mbischoff/.config/fin/z'

in function '__fin_install'
    called on line 201 of file ~/.config/fish/functions/fin.fish
    with parameter list 'z'

in function 'fin'
    called on standard input
    with parameter list 'z'

fin SAYS Done in 1s 993ms