RuntimeError from ProgressBar

Managed to get a repro to a short script (Python 3.7.5 on Windows):

import prompt_toolkit as pt
import sys
import time

def main():
    with pt.shortcuts.ProgressBar() as pb:
        for i in pb(range(80)):
            time.sleep(0.01)

if __name__ == '__main__':
    main()

No prompt comes back. When I hit any key, I get:

exception calling callback for <Future at 0x1d41f1833c8 state=finished raised RuntimeError>
Traceback (most recent call last):
  File "c:\utils\anaconda3\envs\cync\lib\concurrent\futures\thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "c:\utils\anaconda3\envs\cync\lib\site-packages\prompt_toolkit\input\win32.py", line 522, in wait
    loop.call_soon_threadsafe(ready)
  File "c:\utils\anaconda3\envs\cync\lib\asyncio\base_events.py", line 728, in call_soon_threadsafe
    self._check_closed()
  File "c:\utils\anaconda3\envs\cync\lib\asyncio\base_events.py", line 475, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\utils\anaconda3\envs\cync\lib\concurrent\futures\_base.py", line 324, in _invoke_callbacks
    callback(self)
  File "c:\utils\anaconda3\envs\cync\lib\asyncio\futures.py", line 362, in _call_set_state
    dest_loop.call_soon_threadsafe(_set_state, destination, source)
  File "c:\utils\anaconda3\envs\cync\lib\asyncio\base_events.py", line 728, in call_soon_threadsafe
    self._check_closed()
  File "c:\utils\anaconda3\envs\cync\lib\asyncio\base_events.py", line 475, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed

Start with the Windows input implementation at prompt_toolkit/input/win32.py and run the short ProgressBar reproduction on Python 3.7.5 and Windows. Trace the event-loop shutdown and input callback behavior; done means the script returns to the prompt without either RuntimeError shown in the report.