I need new assertion checking the count of elements which the selector matches.
It's very useful to verify the count of elements.

      // before
      await page.waitForSelector(selector);
      const count = await page.$$eval(selector, (el) => el.length);
      expect(count).toBe(1);

      // after
      await expect(page).toHaveCount(selector, 1)

It might be better to co

Let's make sure the matcher was called with supported parameters, fail fast otherwise.

There should be no need in console.error usage.