Roles command not working if a member has a name similar to a joinable role

[rasmusgerdin]

Describe the bug
The new membername feature being implemented across the board a couple weeks back, allowing mods to not have to @ a user when performing moderator actions on them. For the roles command, this breaks it if there's a member in the server with a similar name to a joinable role.

This issue can be circumvented by using -roles add @user role
Discovered in TMG Discord.

To Reproduce
Steps to reproduce the behavior:

1. Have a joinable role called minecraft and a user with a name starting with minecraft.
2. Have a user try to join it using -roles join minecraft
3. User is told to specify a role by it's name.

Expected behavior
The user is added to the role.

Screenshots
Error:

Workaround: