When PLS_URL is not set (in development), logging in with oidc crashes

[foodelevator]

Unlike pkg/pls.check, pkg/pls.GetUserPermissionsForGroup does not make a null check on config.Config.PlsURL.

Not providing an url to pls means to allow everything, so ideally this would then return every permission for the group/system that anyone has (not specifically the user requested). But I kind of think that not supplying the pls url should perhaps not be supported and we should have a better pls thing for local development instead.

Anyways, currently we get invalid memory address or nil pointer dereference which should not be the case.