Stop non-upgraded freshmen from causing errors in UI

Basically line [78](https://github.com/ComputerScienceHouse/conditional/blob/develop/conditional/util/member.py#L78): https://sentry.io/organizations/csh/issues/1867667209/?project=133175&query=is%3Aunresolved needs a check to make sure `freshman_data` ins't None, and if it is, spit out some warning saying to contact evals to upgrade their freshman account