Error propagation

If any coroutine raises an error, then:

1. All coroutines across the entire loop will have tinyio.CancelledError raised in them (from whatever yield point they are currently waiting at).
2. Any functions ran in threads via tinyio.run_in_thread will also have tinyio.CancelledError raised in the thread.
3. The original error is raised out of tinyio.Loop.run. This behaviour can be configured (e.g. to collect errors into a BaseExceptionGroup) by setting .run(..., exception_group=None/False/True).

This gives every coroutine a chance to shut down gracefully. Debuggers like patdb offer the ability to navigate across exceptions in an exception group, allowing you to inspect the state of all coroutines that were related to the error.

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tinyio.CancelledError(BaseException)

Raised when a tinyio coroutine is cancelled due an error in another coroutine.