why do I get a core dump when creating an object?

Question

I am doing some OOP problems and I was provided this code

int main() {
 IntegerArray a(2);//This call the constructor
 a.data[0] = 4; a.data[1] = 2;
 if (true) {
 IntegerArray b = a;
 }
 cout << a.data[0] << endl; // The result is 4
}

I add the indentation to the code and created the class which contains two constructors and a destructor

class IntegerArray
{
    public:
        int *data;
        IntegerArray()
        {
            data = new int[1];
        }
        IntegerArray(int len)
        {
            data = new int[len];
        }

        ~IntegerArray()
        {
            delete data;
        }
};


int main() 
{
    IntegerArray a(2);//This call the constructor
    
    a.data[0] = 4;
    a.data[1] = 2;
    
    if (true) 
        IntegerArray b = a;
    
    printf("%d\n", a.data[0]);
}

The question is why does this code cause a core dump in IntegerArray b = a isn't it copying the object a into a new object b, I guess this is my understanding of Exercise 3

This is the program output

0
free(): double free detected in tcache 2
Aborted (core dumped)