It doesn't make sense to throw/fassert/invariant in functions declared in storage_engine.h anymore, because storage_engine_impl.h always overrides them.

For example in storage_engine.h,
https://github.com/mongodb/mongo/blob/c0ca6049bad1bf918e46d83cddab134b7441abf7/src/mongo/db/storage/storage_engine.h#L398-L423

and correspondingly in storage_engine_impl.h
https://github.com/mongodb/mongo/blob/c0ca6049bad1bf918e46d83cddab134b7441abf7/src/mongo/db/storage/storage_engine_impl.h#L136-L140