Fix error on page.query when no matches with given selector

[ankur22]

What?

This fixes the issue where Page.Query (page.$) returned an error when no elements match the given selector.

Why?

The actual expectation in this scenario, is for the API to return nil.

This was tested with the following script:

Click me

import { browser } from 'k6/experimental/browser';

export const options = {
  scenarios: {
    ui: {
      executor: 'shared-iterations',
      iterations: 1,
      options: {
        browser: {
          type: 'chromium'
        },
      },
    },
  },
}

export default async function () {
  const page = browser.newPage();

  await page.goto("https://test.k6.io");

  const result = page.$('input[name="login"]');
  if (!result) {
    console.log("It's null, hooray!");
  }

  page.close();
}

Checklist

• I have performed a self-review of my code
• I have added tests for my changes
• I have commented on my code, particularly in hard-to-understand areas

Related PR(s)/Issue(s)

Updates: #982

[ka3de]

LGTM.

[ka3de]

LGTM.