This will send an event to a non-existent schema:
ReadingDepthSchema.enable
This was mistakedly kept for backwards compatibility.
It should have been kept for trackSubscribe not track.
The damage is done, so we should just remove this to get
error rates down to a comfortable rate again.
Bug: T207423
Change-Id: Ibb5cc2dd9b486c921aab5f8830e837f813683482