RuntimeError: Event loop is closed - with > 1 workers about python-sitemap HOT 6 CLOSED

INFO:root:Crawling #44: https://up.codes/s/bond-beams
INFO:root:Crawling #45: https://up.codes/s/transformer-efficiency
Traceback (most recent call last):
  File "main.py", line 60, in <module>
    crawl.run()
  File "/home/garrett/_Garrett/upcodes_general/external_repos/python-sitemap-2/crawler.py", line 132, in run
    event_loop.run_until_complete(self.crawl_all_pending_urls(executor))
  File "/usr/lib/python3.7/asyncio/base_events.py", line 579, in run_until_complete
    return future.result()
  File "/home/garrett/_Garrett/upcodes_general/external_repos/python-sitemap-2/crawler.py", line 146, in crawl_all_pending_urls
    for url in self.urls_to_crawl:
RuntimeError: Set changed size during iteration
ERROR:concurrent.futures:exception calling callback for <Future at 0x7fd202b34610 state=finished returned NoneType>
Traceback (most recent call last):
  File "/usr/lib/python3.7/concurrent/futures/_base.py", line 324, in _invoke_callbacks
    callback(self)
  File "/usr/lib/python3.7/asyncio/futures.py", line 362, in _call_set_state
    dest_loop.call_soon_threadsafe(_set_state, destination, source)
  File "/usr/lib/python3.7/asyncio/base_events.py", line 728, in call_soon_threadsafe
    self._check_closed()
  File "/usr/lib/python3.7/asyncio/base_events.py", line 475, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed