`EmptyObject`'s use of non-exported symbol declaration causes TypeScript errors in monorepo environment with project references

[icopp]

In a monorepo environment with project references, using EmptyObject results in an inexplicable error:

Return type of exported function has or is using name 'emptyObjectSymbol' from external module "(path)/node_modules/type-fest/source/empty-object" but cannot be named.

As far as I can tell, this is an unfixed TypeScript bug (they've claimed it's fixed but it obviously isn't) in the difference between interface and type behavior (maybe? see comments).

[icopp]

Actually, with more testing here, the use of interface only works sometimes. This is extremely weird and I don't know for sure what any actual fix is.

This may be some kind of new-ish regression in TypeScript, there are a lot of people very confused about similar errors.