Minecraft v1.16.5
Forge v36.0.1
Fairy Lights v4.0.4

I was on my server testing some machine blocks from Tofucraft when I suddenly crashed client-side. I hadn't placed any fairy lights.
Crash Report

Thanks for reporting! Unfortunately this is an issue on Tofucraft's end, as it appears they have wrongly implement block capabilities.

Oh oof. I'll report it to them.