I would like to keep it as a warning. The result, in our setup, is not incorrect results: rather, it is sub-optimal cache reuse. Issuing a warning will alert the user to this situation without needlessly crashing their code. I could upgrade to `.error`, but don't see a lot of benefit to that. It's perfectly valid to be lazy and create a non-describable, non-serializable custom object if you don't care about great cache reuse.