The_True_OOF

I'm trying to open my server but it can't start with an error message popping up and the starting process terminating a few seconds later. Does anyone have a fix for this? Thanks.

So I was making my RPG server which uses citizens. I soon realised that I could move the citizens by just pushing them. I looked things up and apparently for player citizens you can fix the glitch using /npc collidable or /npc gravity but for villager typed citizens don't work with those commands. So any player can move around my villager typed citizen. Please fix this glitch it could save my whole server. Thanks, The_True_OOF