https://github.com/10gen/mongo/blob/4cf35ce4dc92b1d7557425c223efc0750341ddc8/src/mongo/scripting/mozjs/objectwrapper.cpp#L688

This is a JS integration assertion that checks the BSON size when converting JS objects to BSON.

This is a good limit for $function, but we also use it in legacy shell in our fuzzer tests.

The fuzzer first tries to use a much faster comparison algorithm in C++ before falling back to a slower javascript comparison. And if the query result don't fit into 16 MB, it will only use JS.

Relaxing this limit will help us speed up tests and avoid some JS pitfalls.

It would be great if this limit was configurable via a query knob or something else, so we can make `mongo` accept larger documents.