Dynamic creation of an array in a view Function

Smart Contracts
1

Knowing the problems with the arrays in solidity and its high cost of gas, I thought of creating an array dynamically in a function that will look for the values in a mapping indexed through a counter. I consider that this option is cheaper than the direct storage in an array.

However, it gives me error. It doesn't specify which one because it would compiles me perfectly. I am using a structure as type of the array and I don't know if this is a problem, although I think it shouldn't be.

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract Estructuras {

/// ///     STRUCT ///

    struct Estructura {
        string cadena;
        uint id;
        address direccion;
    }

    Estructura datosUsuario;


    mapping(uint => Estructura) public users;
    mapping(address => bool) public permisos;

    uint public contador;

    function crearUsuario(uint _idNFT, string memory _nombre) public  {

            require(!permisos[msg.sender], "Usted ya esta registrado");
            contador++;
            Estructura memory newEstructura  = Estructura(_nombre, _idNFT, msg.sender);
            users[contador] = newEstructura;
            permisos[msg.sender] = true;


    }

    function createArray() public view returns(Estructura[] memory){

            Estructura[] memory array;
            for(uint i = 0; i < contador; i++){
            array[i] = users[i + 1];      
            }
            return array;

    }

}

Where is my mistake?

2

The solution:

function createArray() public view returns(Estructura[] memory) {
  Estructura[] memory array = new Estructura[](contador);
  for(uint i = 0; i < contador; i++){
     array[i] = users[i + 1];
   }
   return array;
}