- fixed issue 74: don't assume that a further session status change
(e.g. ended, finalized) exists after the last lap
- improved error handling if there exists no usable lap data for any
driver (73, e.g. Imola 2021 FP1)
- `fastf1.core.get_session` should not quietly return
`fastf1.core.Weekend` instead of `fastf1.core.Session`
if an invalid event name is given.