[BUG] Registering actor reminder with empty state results in error while receiving it

[natasky]

Expected Behavior

Following code snippet should result in a functioning actor reminder -

await self.register_reminder(
    "my_reminder,
    state=b"",  # <-- EMPTY STATE
    due_time=timedelta(minutes=1),
    period=timedelta(minutes=1),
)

The issue arises from ActorReminderData - __init__ fails for None state (though typing annotations suggest its valid), yet from_dict explicitly sets state to None if its empty.

Actual Behavior

Reminder is registered and daprd does fire it, but the Python SDK fails with code 500 when receiving it. Sample logs from daprd:

2025-02-15T09:23:39.012571944Z time="2025-02-15T09:23:39.012454243Z" level=error msg="Error invoking reminder on actor MyActor||MyActorID: error from actor service: {\"message\":\"ValueError(\\\"only bytes are allowed for state
: <class 'NoneType'>\\\")\",\"errorCode\":\"UNKNOWN\"}" app_id=my-app instance=my-app-instance scope=dapr
.runtime.actor type=log ver=1.14.4

Steps to Reproduce the Problem

Start app with the actor from snippet.

Release Note

RELEASE NOTE: FIX receiving reminders with empty state.