Error: Evaluation failed: ReferenceError in waitForFunction

When calling the following code:

[...]
const options = {
	page: await browser.newPage()
};
await utils.fetchPage("someurl", ".some-selector", options);

with the following fetchPage implementation:

async function fetchPage(p_url, p_waitForSelectors, p_options) {
	assert(p_options.hasOwnProperty('page'));

	await p_options.page.goto(p_url, {waitUntil: 'networkidle2'});

	if (p_waitForSelectors) {
		await p_options.page.waitForFunction(() =>
			document.querySelectorAll(p_waitForSelectors).length
		);
	}

	const html = await p_options.page.content();
	assert(html);
	return html;
}

I get the error:

[17:39:49] [ERROR]  Error: Evaluation failed: ReferenceError: p_waitForSelectors is not defined
    at eval (eval at waitForPredicatePageFunction (:2:23), <anonymous>:4:30)
    at eval (eval at waitForPredicatePageFunction (:2:23), <anonymous>:4:57)
    at onRaf (<anonymous>:49:35)
    at pollRaf (<anonymous>:42:15)
    at waitForPredicatePageFunction (<anonymous>:7:22)
    at ExecutionContext._evaluateInternal (\node_modules\puppeteer\lib\cjs\puppeteer\common\ExecutionContext.js:217:19)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
    at async WaitTask.rerun \node_modules\puppeteer\lib\cjs\puppeteer\common\DOMWorld.js:528:23)

When replacing p_waitForSelectors with the explicit string literal ".some-selector" all works fine:

[...]
		await p_options.page.waitForFunction(() =>
			document.querySelectorAll(".some-selector").length
		);
[...]

Is this some weird JavaScript quirk that I somehow misunderstand? Or is this a genuine bug?

I’m using Puppeteer 5.5.0.

[MarByteBeep]

That fixed it! @vsemozhetbyt thanks so much for the help!

[cloydlau]

It finally works by adding:

const fnStr = fn.toString()
  .replace(/\/\* istanbul ignore next \*\//g, '')
  .replace(/cov_.+\(\)\..+]\+\+;/g, '')
  .replace(/cov_.+\(\)\..+]\+\+,/g, '')

new Function('return ' + fnStr)()()

Now I’m working on how to get the result of fn