Use `$commands[]` to check for command existence

lib/theme-and-appearance.zsh

@@ -19,7 +19,8 @@ then
     colorls -G -d . &>/dev/null 2>&1 && alias ls='colorls -G'
   else
     # For GNU ls, we use the default ls color theme. They can later be overwritten by themes.
-    type dircolors >/dev/null 2>&1 && eval "$(dircolors)"
+    (( $+commands[dircolors] )) && eval "$(dircolors)"
+
     ls --color -d . &>/dev/null 2>&1 && alias ls='ls --color=tty' || alias ls='ls -G'
   fi
 fi