Save bug.
So there’s a problem with the world map save feature, where sometimes it saves in an unstable state and crashes on reloading. Trying to resolve this but in the meantime I suggest saving in the party select screen rather than on the world map itself, especially after using a tent.
Apparently it's an issue with outdated software, changed the download. Or you could replace the old rpg_rt.exe file with this:
https://rpgmaker.net/media/content/users/147430/locker/RPG_RT.exe
Highly recommend redownloading though.