Bugfix/266 load path access type

[nathanjmcdougall]

To fix #266.

[nathanjmcdougall]

I realize that in my tests, I am mocking using a restricted Meta protocol similar to what is described in #12:

Alternatively, there could be a stripped down version for Meta (or an interface), that defines the bare minimum required for data loading (i.e. type, filename).

This might be an opportunity to formally define a Protocol class and refactor the test suite accordingly.

[isabelizimm]

small naming nit, but otherwise looks good! Thank you for the tests as well 🙌