Summary:
We are getting some clippy warnings about [complex types](https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity), related to eqwalizer queries on salsa, e.g.
```
Result<Arc<BTreeMap<ModuleName, BTreeMap<Id, Arc<TypeDecl>>>>, Error>;
```
We believe this type is clear enough, so raise the threshold of the clippy lint to allow it.
Also fix one other clippy warning about unreachable code.
Reviewed By: ilya-klyuchnikov
Differential Revision: D74248916
fbshipit-source-id: 7e9e603729ce480a6c193f9cba6129ee637be880
