I try to use sushi (which offer similar feature like Quick Look on MacOS ) on Ubuntu 19.04. Got this error:
(sushi-start:8478): Gjs-WARNING **: 15:07:50.705: JS ERROR: Error: Requiring Sushi, version none: Requiring namespace 'GtkSource' version '3.0', but '4' is already loaded
@/usr/share/sushi/js/viewers/text.js:33:7