[JIRAALIGN-1277] Ideation: 500 error thrown when accessing public URL

Issue Summary

When accessing an Idea group via the public URL a 500 error is thrown

Steps to Reproduce

1. Create a new Ideation group and set it to public.
2. Copy the External Link and paste into a new browser session.
3. Click register (or login)
4. Supply details/login credentials

Expected Results

The user is taken to the Ideation portal.

Actual Results

500 server error is thrown - note this is not a Whoops error, rather a hard 500.

We see the following logging around the event:

GET /ideaZone/ideas FirstTime=True&GroupSection=<GROUP_TOKEN>|4374|800a005e|Invalid_use_of_Null:_'Replace' 443 - 172.26.168.160 Mozilla/5.0+(Windows+NT+10.0;+Win64;+x64)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/80.0.3987.132+Safari/537.36 
...
https://<SITENAME>/ideaZone/ideas?FirstTime=True&GroupSection=<GROUP_TOKEN> 500 0 0 143

Workaround

Removing the "FirstTime=True" from the URL allows access, so the URL to use would look like:
_https://<SITENAME>/ideaZone/ideas?GroupSection=<GROUP_TOKEN>_