(New) Fix crash on previewing challenge with no category (#466)
(New) Fix crash on previewing challenge with no category (#466)

* Fix crash on previewing challenge with no category

The program didn't call the right function when displaying a challenge with no category. This fixes that.
mitre-cyber-academy/registration-app,mitre-cyber-academy/ctf-scoreboard,mitre-cyber-academy/ctf-scoreboard,mitre-cyber-academy/registration-app,mitre-cyber-academy/registration-app,mitre-cyber-academy/ctf-scoreboard,mitre-cyber-academy/ctf-scoreboard