Code conflicts with closing winform, how to fix it?

Question

C++ / C#

https://cloud.mail.ru/public/KgHg/AVhEYgMoF
Please watch the video and help please))

Answer 1

NullReferenceException is usually thrown if somewhere there is a call to something, but the object itself has not been created yet.
I will give an example you have a class Person

class Person
    {
        public string Name;
        public string Surname;
    }

You do like this:

class Program
    {
       static Person person;

        static void Main(string[] args)
        {
            person.Name = "Jim";

            Console.WriteLine(person.Name);
            Console.ReadKey();
        }
    }

This code will also throw a NullReferenceException. And all because you did not initialize the class.
See your code. Apparently you do not create an object. Or maybe it is created, but much later than you are trying to call it.