ConcurrentModificationException when arenas are loaded from disk

[Chumb3x]

There is some random error with the plugin. The error fixes itself whenever the plugin is reloaded. There are 7 areas and others work fine except this 3.

https://paste.gg/p/anonymous/40549a621e534ddb9b5d5efb19198070

[StrangeOne101]

Will look into