as default properties of the currentUser query.
We don't need it all the time. Somewhere in the frontend, the call to
`fetchCurrentUser` is abused to refresh some data of the user to be
edited.
* refactor store/auth.js not to use `delete Object`
* refactor store/auth.js to have less redundancy
* implement fetchCurrentUser without knowing the id beforehand
* test fetchCurrentUser and init
This is why I ❤️ testing. First I wrote several tests to get
familiar with the existing code and specified everything that I believe to
be required. Then I refactor the entire method at once and the tests pass.
Note that I do **not** believe that setting the user data to `null` is
really relevant.
