Materializer crashing because of failed assumptions

[sentry]

Unclear how exactly, but the materializers for subqueries have been seen crashing with 2 distinct issues:

1. KeyError when seeing a delete (because we're assuming a shape will never see a delete without seeing an insert, much less the materializer)
2. "duplicate key" when seeing an insert (because we're assuming for a given key we'll never see 2 distinct inserts on the same key)

[icehaunter]

This is happening on a shape where there is a col1 = 1 OR col2 IN (SELECT ... )