I have found the source of the issue.
In the bootstrap.php of the Kikioboeru/Kikioboeru it is trying to load some stuff from the options table.
However, I cannot find a better place to put this in since this code has to run when the plugin gets loaded.
See this topic for why I placed it here.
After some looking around, I figured I should place this in the AppController:initialize instead, which resolved the issue for me.
One slight issue though, is that moving this to the AppController:initialize for said plugin, only runs this code when that plugin is actually used, instead of when it’s loaded.
Any workaround for this?