Final underscore on username

[intersecato]

I noticed that you can't create users whose usernames end with an underscore. Is this a design choice for some reason, or is it a bug? Even just logging in with OIDC results in a generic error.

[nastyagrifon]

Can confirm that entering username with underscore at the end and pressing "Add user" does not create the user. Happens only with username.

ghcr.io/plankanban/planka:2.0.0-rc.4

[intersecato]

I also noticed that the username can't even begin with an underscore, not just at the end.