I am redirecting a ticket I got to RFTools, as my mod isn't showing up in the log, but rf tools is

AbsolemJackdaw/PublicGuiAnnouncement#1

this old ticket got reopened for it, and has some more detail.

a short resume of the issue :

Cyclops Core checks for capabilities not being null

https://github.com/CyclopsMC/CyclopsCore/blob/release-/src/main/java/org/cyclops/cyclopscore/modcompat/capabilities/DefaultCapabilityProvider.java#L21

Pga used to have this issue due to complications.
That issue got once resolved, and doesn't figure in the latest crash the end user has submitted.

I myself, for my mod, got the issue resolved by :

providing a lazy optional (which I didn't do before)

src/main/java/subaraki/pga/capability/ScreenData.java

and by fixing a registry issue

AbsolemJackdaw/PublicGuiAnnouncement#2

I have no further detail as the end user hasn't given any more.

Closed issue, moved to correct repo.