If the cancel button is pressed on biome creation when adding new entities to the list of entities to spawn in the new biome, null elements are added to the list and this causes recompilation errors.
MCreator issue tracker has been migrated to GitHub.
Existing tickets have been migrated to GitHub. Please open new tickets on the GitHub tracker instead. If you do not have a GitHub account, all feature requests and bug reports from forums are still considered and checked by the maintainers.