Type annotations are ignorred when module contains error

E.g.

```reason
let foo = (arg: array(Foo.t)) => ... some error here ...
/* ^ */
/* hover, cmd+click etc don't work */
```

Reproduce the Reason example in a language-server client with a module-level error, then inspect how the server handles the type annotation near the error. Confirm the fix by checking that hover and cmd-click work for the annotation while the surrounding module still contains an error.

Written by the indexing model from the issue text.