While wearing two pieces of hexerei armor (which is supposed to prevent witches from attacking you), if you approach a witch, the server crashes. By changing removeErroringEntities to true in world/serverconfig/forge-server.toml, I am able to join and the witch is immediately removed. By removing the armor pieces, i am able to stand near witches again without them being removed.
Relayed from https://github.com/EnigmaticaModpacks/Enigmatica9/issues/525 Using hexerei-0.3.2.2.jar