Finish marking CVR export as complete before setting polls store state to closed in backend polls-close handler

[arsalansufi]

Relevant handler:

vxsuite/apps/scan/backend/src/polls.ts

Lines 50 to 95 in 21231af

	export async function closePolls({
	workspace,
	usbDrive,
	logger,
	}: {
	workspace: Workspace;
	usbDrive: UsbDrive;
	logger: Logger;
	}): Promise<void> {
	const { store } = workspace;
	const previousPollsState = store.getPollsState();
	assert(
	previousPollsState === 'polls_open' || previousPollsState === 'polls_paused'
	);
	store.transitionPolls({ type: 'close_polls', time: getCurrentTime() });
	await logger.logAsCurrentRole(LogEventId.PollsClosed, {
	disposition: 'success',
	message: 'User closed the polls.',
	});
	if (previousPollsState === 'polls_open') {
	const ongoingBatchId = store.getOngoingBatchId();
	assert(ongoingBatchId !== undefined);
	store.finishBatch({ batchId: ongoingBatchId });
	await logger.log(LogEventId.ScannerBatchEnded, 'system', {
	disposition: 'success',
	message: 'Current scanning batch finished on polls closed.',
	batchId: ongoingBatchId,
	});
	}
	const ballotsCounted = store.getBallotsCounted();
	if (ballotsCounted > 0) {
	const exportResult = await exportCastVoteRecordsToUsbDrive({
	mode: 'polls_closing',
	workspace,
	usbDrive,
	logger,
	});
	exportResult.assertOk(
	'Failed to finish cast vote record export to USB drive.'
	);
	}
	}

Today, we set the polls store state to closed first, then mark the CVR export as complete. If the latter fails, you run the risk of the export being left in a bad state, with your only course of corrective action being a slow full re-export. By switching the order of operations, you'd be able to correct things by just trying to close polls again, a much faster operation.