Question

    public Alphabet(params char[] list)
    {
        this.ExceptionInitializer();
        try
        {
            if (list != null) _alphabet = list;
            else throw this.NullableAssignment; //add exception handler;
            this._charCounter = list.Length;
        }
        catch (this.NullableAssignment)
        {
          //  var x = new Alphabet();   
          //  this = x;      //FAIL!
        }
    }

Answer 1

You can’t do this – the closest thing would be to create a static factory method which returns an Alphabet:

public class Alphabet
{
    private Alphabet(params char[] list)
    {
         //setup
    }

    public static Alphabet Create(params char[] list)
    {
        return list == null
            ? new Alphabet()
            : new Alphabet(list);
    }
}

Although given your example, even simpler would just be to assign an empty array in the place of null:

public Alphabet(params char[] list)
{
    _alphabet = list ?? new char[] { };
    this._charCounter = _alphabet.Length;
}