Almost hate to post this, because I dont have much info to share.
Installed this extension, turned it on, and it seemed to have no effect. The new link/buttons didnt show to select a best answer in forum posts.
Continued to install other extensions. (This is on a new install by the way)
Installed emojionearea next.
After doing a few other things... the forum suddenly broke completely.
php log showed nothing, nginx log showed nothing, web console showed nothing.
flarum debug was ON.
I uninstalled emojionearea and everything remained broke. Cache clear. Still broke.
After pulling my hair out for a few hours, started removing extensions from the command line using composer, one by one. Cleared flarum cache after every uninstall and hit refresh.
Once I removed the BEST ANSWER extension, everything started working again.
Again, sorry I dont have any more clues to provide, but something funky going on.
Broke my forum in a way that made it nearly impossible to debug.