In this case, the duration of the budget cannot be determined, and the
application was crashing when trying to do so.
Now we're just returning `nil` as duration.
There's an edge case where the current phase of the budget was disabled.
In this case, the application was crashing.
I'm not sure what we should do regarding this case. Is it OK to allow
disabling the current phase? Is it OK to allow selecting a disabled
phase as the current phase?
Since I'm not sure about it, for now I'm leaving it the same way it was.
Co-authored-by: Julian Herrero <microweb10@gmail.com>