StreamReader reports null if no new events exist.

[dealproc]

In the following code snippet:

	private TaskCompletionSource _refreshTCS = null!;
	public Task RefreshAsync() {
		if (_refreshTCS != null)
			return _refreshTCS.Task;

		_refreshTCS = new();
		Task.Run(() => {
			using (var reader = _connection.GetReader($"{nameof(CartDetailsRm)}-ctor", Handle)) {
				reader.Read<Cart>(_cartId, () => Idle, checkpoint: _cartCheckpoint);
				// this seems like bad juju.  is this a bug?
				_cartCheckpoint = reader.Position is null
					? _cartCheckpoint
					: reader.Position;

				_refreshTCS.SetResult();
				_refreshTCS = null!;
			}
		});

		return _refreshTCS?.Task ?? Task.CompletedTask;
	}

In the event that the read from reader.Read<TAggregate>([id], () => Idle, checkpoint: ...) does not read anything new from the provided checkpoint, reader.Position reports null, when it should report the current position (in my opinion)