Indefinite Integrals Don't evaluate correctly

[exoRift]

Description

The integration function doesn't seem to function correctly. It can't compute an antiderivative in some cases and in others it's plain wrong

Steps to Reproduce

import { ComputeEngine } from '@cortex-js/compute-engine'

const ce = new ComputeEngine()

console.log(ce.parse('\\int (2x)\' dx').evaluate().toLatex())
// Expected: Something equiv to: 2x
// Actual: \int\!x\mapsto2x^{\prime}\, \mathrm{d}x

console.log(ce.parse('\\int x \\sin(x) dx').evaluate().toLatex())
// Expected: Something equiv to: -x cos(x) + sin(x)
// Actual: \frac{1}{2}(\sin(x)x^2)-x\cos(x)

console.log(ce.parse('\\int 2x dx').evaluate().toLatex())
// Expected: Something equiv to: x^2
// Actual: 3x^2

console.log(ce.parse('\\int 2x^3 dx').evaluate().toLatex())
// Expected: Something equiv to: \frac{1}{4} x^4
// Actual: \frac{5x^4}{2}

Environment

Compute Engine version 0.30.2

[DamitusThyYeetus123]

It got sqrt(x) wrong too, returned 2/3 x^3 instead of 2/3 x^3/2
also can't accurately do chain integrals such as sin(x^2)