RuntimeWarning: coroutine 'PersistentDict.backup.<locals>.backup' was never awaited

[rodja]

Description

Running multiple storage operations yield an error that the backup coroutine was never awaited. Reproduction

from nicegui import app, ui

def test():
    app.storage.general['one'] = 1
    app.storage.general['two'] = 2
    app.storage.general['three'] = 3


# ui.button('run test', on_click=test)
ui.timer(1, test, once=True)

ui.run(storage_secret='secret')

The timer will already produce the error. Swapping the timer with a button yields the same error on first button press. The issue was originally reported on Discord. I suspect something strange with our background_tasks.create_lazy function.

[falkoschindler]

Interesting... Reproduction without storage:

ui.button('sleep', on_click=lambda: (
    background_tasks.create_lazy(asyncio.sleep(0.1), name='sleep'),
    background_tasks.create_lazy(asyncio.sleep(0.2), name='sleep'),
    background_tasks.create_lazy(asyncio.sleep(0.3), name='sleep'),
))

Apparently it takes three tasks to get a warning.