过早关闭嵌套异步生成器

我正在研究如何在不完全迭代的情况下关闭嵌套异步生成器。例如:

import asyncio


async def gen1():
    yield 1
    yield 2


async def gen2():
    async for nr in gen1():
        yield nr


async def main():
    stream = gen2()
    print(await stream.__anext__())  # 1
    await stream.aclose()


asyncio.run(main())

但是,这会导致 RuntimeError

unhandled exception during asyncio.run() shutdown
task: <Task finished name='Task-2' coro=<<async_generator_athrow without __name__>()> exception=RuntimeError("can't send non-None value to a just-started coroutine")>
RuntimeError: can't send non-None value to a just-started coroutine