I've been having Reap Soul issues and I think I finally figured out why. I think the spell id for deadwind_harvester_buff is wrong (says 214867, but I think it is really 216708). The problem manifests itself as a suggestion to cast Reap Soul, even when you have an existing Deadwind Harvester buff (sometimes much longer buff than you'd get if you ate your currently available souls).

@alarge can you please check the changes as shown in Hemario@98126f9 and say if this does in fact solve your issue?
I have no warlock on my own, so can't verify

Commented directly on the commit, but yes, I think this is the right change.