bug: Wrong data showing in table tab if fitness data empty

[andreped]

This bug seems to happen if you have yet to add any fitness data, but you open the fitness table in the table tab anyways. This results in the wrong data being rendered like seen below.

When you then try to add new fitness data through the logging tab, it does not work. This is because the caching from using the wrong data results in the table in a corrupt state, somehow.