Passing objects to class library

I want to move some code to class library. I have a class library with a class like the one below:

[Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
public class AccountStats : Robot
{
    private Robot cBot;
    
    public AccountStats(Robot robot)
    {
        cBot = robot;
    }
    
    // (...)
}

I use OnStart() to initialize an object:

Stats = new AccountStats(this);

But I get errors “Object Reference Not Set To An Instance…” for example when using the code below inside class library:

var netProfit = cBot.History
                .Where(x => x.ClosingTime.Date == Server.Time.Date.AddDays(days))
                .Sum(x => x.NetProfit);

I believe that is caused by the fact that inside library class there is no instance of “Server” object?

In that case, what typical set of objects should I pass to external class library to use most common methods? Obviously I need to pass the main “robot” (as in constructor above). Now I know I should pass “Serwer” object. What else?

I know this is kind of silly question and the answer is “pass those objects you will use”. But I have great difficulty in debugging when I get “Object reference…”, so I would like to minimize risk of such crashes. And maybe I should not pass individual object and there is a solution to use all methods from within class library the same way I would use then inside main cBot?

UPDATE: Clearly I don't uderstand this because expanding the constructor to IServer obecjt did not change the behaviour

    public AccountStats(Robot robot, IServer server)
    {
        cBot = robot;
        cServer = server;
    }
    
    public double DaysProfit(int days)
    {
        double netProfit;  

        netProfit = cBot.History
                .Where(x => x.ClosingTime.Date == cServer.Time.Date.AddDays(days))
                .Sum(x => x.NetProfit);
        
        return netProfit;
    }