The new H- photo-detachment and H2II photo-dissociation fields added in PR #401 weren't getting initialized, causing an error in Grid_IdentifyRadiativeTransferFields.
Woops - I missed that when porting across from my Enzo-3.0 fork. I just checked and they are in that fork but didn't make it across. Good catch! The tests didn't seem to pick this up though - at least they passed for me without this change. Where did the failure arise for you? Can you also review PR #409 as that has other bug fixes that needs to get pulled in?
Passes the test suite, and looks good to me. Approved!