Under Certain Conditions, Null Reference Error is thrown during whoami command

[TheDrakonLord]

Describe the bug
Certain users trigger null reference exception when using whoami

To Reproduce
Steps to reproduce the behavior:

1. User uses iam successfully
2. User uses whoami
3. Error: character not found thrown
4. Null reference error written to log

Expected behavior
Character embed should be displayed

Screenshots

Additional context
Known users with issue: Leo, Lali

[TheDrakonLord]

It was eventually determined that this was caused by discord users having invalid characters in their username. to resolve this issue, the bot now uses discord IDs as the index rather than the username.

[TheDrakonLord]

New users with this issue have been identified, it does not seem that the cause is related to previous instances of this issue.

Users: Maelin [Havoc] (may not have used !iam), Daedelise [Havoc]