postInstall = ''
mkdir -p $out/share/glib-2.0/schemas/
glib-compile-schemas --targetdir=$out/share/glib-2.0/schemas $src/data
wrapProgram "$out/bin/ilia" --set XDG_DATA_DIRS "$out/share/gsettings-schemas/ilia-3.1"
'';
Mentioning 3.1 in wrapping the binary can cause future errors when the main package version would be updated.