detect_screen() for "install.sh -c GUI" ?

[chlohr]

Hello,
Does "install.sh -c GUI" do what it is supposed to do?
I'm surprised by the detect_screen() function.

languagetool/install.sh

Line 389 in 37e19c7

if ! [ "$(type -t DISPLAY)" ]; then

DISPLAY is usually an environment variable mandatory for X11, not a shell command.
So, why testing it with " if ! [ "$(type -t DISPLAY)" ]; then ..." and not " if [ -z "$DISPLAY" ]; then ... " ?
Have I missed something?

Best regards
Christophe