No error reported when module doesn't match interface

Nobody has claimed this yet.

When I add an incorrect type to an `rei` file, there's no indication in vscode that compilation failed; the problems tab is empty. From the lsp logs (included below, but I'm happy to add more... it was hard to know what the relevant parts were), the language server seems to be aware of the fact that compilation failed.

Project structure:

- src
- ReludeRandom_Generator.re
- ReludeRandom.re
- ReludeRandom.rei

...where `ReludeRandom.re` has an alias like `module Generator = ReludeRandom_Generator;` and the interface for Generator lives in `ReludeRandom.rei`. If it helps, the whole project structure [is available here](https://github.com/reazen/relude-random/blob/e5d58723f5e96e177eb19187af5d15b818b0ad4e/src/ReludeRandom.rei).

```
>> Build system running: /home/michael/Projects/reazen/relude-random/node_modules/bs-platform/lib/bsb.exe -make-world
>>> stdout
bsb: no work to do.
bsb: no work to do.
bsb: no work to do.
[1/2] Building src/ReludeRandom.cmj
FAILED: src/ReludeRandom.cmj /home/michael/Projects/reazen/relude-random/src/ReludeRandom.bs.js
/home/michael/Projects/reazen/relude-random/node_modules/bs-platform/lib/bsc.exe -nostdlib -bs-package-name relude-random -bs-package-output commonjs:src -color always -bs-suffix -bs-read-cmi -I src -I /home/michael/Projects/reazen/relude-random/node_modules/bs-abstract/lib/ocaml -I /home/michael/Projects/reazen/relude-random/node_modules/relude/lib/ocaml -I /home/michael/Projects/reazen/relude-random/node_modules/bs-platform/lib/ocaml -w -30-40+6+7+27+32..39+44+45+101 -warn-error +A -o src/ReludeRandom.cmj src/ReludeRandom.reast

We've found a bug for you!
/home/michael/Projects/reazen/relude-random/src/ReludeRandom.re

The implementation /home/michael/Projects/reazen/relude-random/src/ReludeRandom.re
does not match the interface src/ReludeRandom.cmi:
...
In module Generator:
Values do not match:
let sample: list('a) => t(option('a))
is not included in
let sample: list('a) => t('a)
File "/home/michael/Projects/reazen/relude-random/src/ReludeRandom.rei", line 138, characters 2-31:
Expected declaration
File "/home/michael/Projects/reazen/relude-random/src/ReludeRandom_Generator.re", line 107, characters 4-10:
Actual declaration

FAILED: subcommand failed.
>>> stderr

Affected files: file:///home/michael/Projects/reazen/relude-random/src/ReludeRandom.re
Cleaning bsconfig.json
Sending notification {"jsonrpc": "2.0", "method": "textDocument/publishDiagnostics", "params": {"uri": "file:///home/michael/Projects/reazen/relude-random/bsconfig.json", "diagnostics": []}}
```

Reproduce the mismatch using the ReludeRandom.re, ReludeRandom.rei, and ReludeRandom_Generator.re structure described in the report. Start by tracing the failed build output and the textDocument/publishDiagnostics notification for bsconfig.json; done means the interface mismatch appears in VSCode's Problems tab instead of an empty diagnostic list.

Written by the indexing model from the issue text.