aliases: only set alias ls to lsd if lsd is a command and if not in a tty (defaults to not being in a tty)

.config/shell/aliases

@@ -59,10 +59,12 @@ command -v paru > /dev/null && alias
    parue="$(which paru) --color=auto --sudoloop --newsonupgrade --pgpfetch --upgrademenu --bottomup --fm nvim" \
    paru='parue --skipreview'                                                                                   \
 
-if command -v lsd > /dev/null; then
-   ! $IS_TTY && alias ls=lsd
+# TODO: make sure IS_TTY is set to a value in the env file, in case the profile is not installed.
+if command -v lsd > /dev/null && ! ${IS_TTY:-false}; then
+   alias ls=lsd
    alias lsd='lsd --group-dirs=first'
 fi
+
 # <<<
 ## Mini short-hand scripts (ex: glone = git clone) >>>
 # dotfile management