[BUG] Test command fails right after initialising a guida project

Run `guida init --yes` to get an initial guida project, as well as a `tests/Example.guida`.

Running `guida test` fails in the following way:

```
% guida test
Starting tests
No exposed values of type Test found in the tests/ directory.

Are there tests in any .elm file in the tests/ directory?
If not – add some!
If there are – are they exposed?
```