Sometimes: Object Null Exception when using var rdr = await cmd.ExecuteReaderAsync();

public async Task<GetNavigationBarBulletsContent> Get([FromServices] MySqlDataSource dbBroadcast )
{
        await using var conn = await dbBroadcast.OpenConnectionAsync();
        string qChannelsToScan = "SELECT channel_id FROM channels_members WHERE member_id = @my_id";
        using var cmdChannelsToScan = new MySqlCommand(qChannelsToScan, conn);
        cmdChannelsToScan.Parameters.AddWithValue("my_id", internal_id);
        using var rdrChannelsToScan = await cmdChannelsToScan.ExecuteReaderAsync(); // Here is the NullException thrown
}