Thread:Extension talk:CategoryTree/Permissions issue using version c7333ea on mediawiki 1.23

I've an issue with some users with restricted (read only) access being unable to expand any node, seeing the tree wherever it is rendered, but getting a load failure, try again later message whatever node they try to expand.

I suspect it is an incompatibility with my own extension Extension:NSWhitelist but haven't been able to figure out what, yet.

I've ruled out browser issues, and a user with full rights can use it fine. Can someone tell me what user rights are needed to expand a node? Must you be able to read a particular namespace?