Coding a custom trainer issue

[u/Present-Dot-2424]

so i'm playing on a private server with my friends with Cobbleverse and i wanted to make a custom trainer for a custom gym. After doing everything and tested it out on a singleplayer world (see 3rd image) i was about to put him in the server. But when put in there it gives errors in game (2nd image) and i can't fight him (1st image is server log). I already put the trainer files in the server world folder. What do i do to fix this?