Unless it's in the exclusion list, it shouldn't display this message. Please paste your log in the github issues..... you can also temporarily downgrade to an older edition from the github releases page or the versions page on mozilla https://addons.mozilla.org/en-US/firefox/addon/volume-control-boost-volume/versions/
Hope I can help you resolve your problem and you can revise your review to 5 stars. I jut do this as a hobby.