Pyppeteer not extracting javascript coverage correctly

When I'm using pyppeteer for extracting js coverage, there is missing some parts of the javascript code.

What I'm doing is the following:

import asyncio
import json
import os
from pyppeteer import launch


def process_coverage(coverage):

    resources = []

    for entry in coverage:
        url = entry['url']
        text = entry['text']

        used_resource = ''

        for interval in entry['ranges']:
            start = interval['start']
            end = interval['end']
            used_resource = used_resource + text[start:end]

        resources.append(used_resource)

    return resources

def save_to_new_file(path, content):
    file = open(path, 'w') 
    file.write(content) 
    file.close()

async def main():

    browser = await launch()
    page = await browser.newPage()

    await page.coverage.startJSCoverage()

    await page.goto('http://127.0.0.1:8000/', option={'waitUntil': 'load'})
    await page.setViewport({ 'width': 500, 'height': 500 })
    await page.setViewport({ 'width': 1920, 'height': 1080 })

    js_coverage = await page.coverage.stopJSCoverage()
    js_resources = process_coverage(js_coverage)

    for idx, resource in enumerate(js_resources):
        save_to_new_file(f'{idx}.txt', resource)

    await page.close()
    await browser.close()

asyncio.get_event_loop().run_until_complete(main())

For example, some screenshots are left here (what it was extracted with the pyppeteer code vs the coverage report that I ran on the chrome browser):

Another example:

As shown on the screenshots, there is code that is missing and on the chrome coverage report shows that was used. Does anyone know what am I missing? Am I missing some configuration?

Edit: I also have found a link in which they have the same problem. The thing is that I don't understand the approach they have taken to solve the issue: https://github.com/puppeteer/puppeteer/issues/1054