Errors in Using alias this = arr within a Class

```d
class A
{
    int [] arr;
    alias arr this; 
}

void main()
{
    A a = new A;
    a ~= 1;  
    writeln(a); // output: [1]
    writeln(a); // output err: []
}
```

When attempting to print the value of variable a for the second time, an error occurs, and the result is an empty array [].