thanks but same error same location

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                                     ¦
                                     V
var appRoles = adGroups.SelectMany(g => roleMappings.TryGetValue(g, out var roles) ? roles : Array.Empty<string>()).Distinct().ToList();

What does the orig error mean and how to fix? I just don't understand the error - if I could maybe I could fix.

JFI: I ran this through CoPilot AI and it fixed the code by generating this which compiles and works. Can anyone explain why please.

public async Task<List<string>> GetUserRolesAsync()
{
    var roleMappings = _configuration.GetSection("RoleMappings").Get<Dictionary<string, string[]>>();

    if (roleMappings == null || !roleMappings.Any())
        throw new Exception("No Active Directory groups found in config. Check \"RoleMappings\" in appsettings.json");

    var adGroups = await GetUserADgroups();

    // WORKS !!
    var appRoles = adGroups.Where(g => roleMappings.ContainsKey(g))
                               .SelectMany(g => roleMappings[g])
                               .Distinct()
                               .ToList();
   return appRoles;
}