Root Causeorg.xwiki.contrib.oidc.provider.internal.OIDCException: Invalid state: was expecting [3f-A4rAOQaSFQ5zmqOinU87LQiDNSsLTKSphUEhSfE4] and got [liul7jao9E2E7FS15LtIkIw4hdjuWe8o_cTxcEM5ttQ]

OK, so that's why it failed. Looks like the nonce sent back by the provided is not the one sent by the client.

In any case, the problem is beyond getting a "more user-friendly error message" as I don't see any valid reason to have this error.