laryr

Hi, I've made a minecraft creative world in Valhelsia 3(via the curseforge launcher). I played it for a few hours, and then left to play a LAN world with the same modpack. (I hosted it) I try to return to the creative world and I get this message. I press "safe mode" and the game freezes for a bit and then does nothing. I'm not too sure how to send logs or anything like that, so if y'all could help me through that as well, that'd be great. Thank you.