···8888 }
89899090 if entry.CID.String() == proposedPrev {
9191- // TODO confirm what should happen if proposedPrev points to a nullified operation. we should probably be ignoring nullified ops here, but confirm with the reference impl
9191+ if entry.Nullified {
9292+ return OperationEffects{}, stacktrace.Propagate(ErrInvalidPrev, "prev operation is nullified")
9393+ }
9294 proposedPrevOp = mo.Some(entry)
9395 break
9496 } else {