pragma solidity ^0.4.24;
import "./Second.sol";

contract First {
    Second private _oSecond;
    int32 public _nRes1;

    constructor(address oSecond) public payable {
        _oSecond = Second(oSecond);
        _nRes1 = 3;
    }
    function TestError() public {
        _oSecond.State();
        //_oSecond._nRes2();  // the problem call is here
        _nRes1 = 5;
    }
}

pragma solidity ^0.4.24;

contract Second {
    int32 public _nRes2;

    constructor() public {
        _nRes2 = 15;
    }
    function State() public {
        _nRes2 = 17;
    }
}

(async () => {
    await first.methods.TestError().send({from: accounts[0]});
    var nRes = await first.methods._nRes1().call({from: accounts[0]});
    console.log(nRes);

    var nRes = await second.methods._nRes2().call({from: accounts[0]});
    console.log(nRes);
})();