Adds an error catch for null responses

[lomky]

Checks if the API has responded with what we consider a null response, and logs that case clearly.

===

Resolves #480

• Relevant documentation (e.g. READMEs, Technical Foundation) updated
• Issue AC are copied to this PR & are met
• Manual Browser Testing performed (with modheader, either locally or on BrowserStack)
• Changes are tested on Staging post-merge into main

[rocketnova]

If you include this, you are in effect making it so that this is unreachable:

ui-claim-tracker/utils/queryApiGateway.ts

Lines 183 to 190 in d79ff60

	if (apiData?.uniqueNumber !== uniqueNumber) {
	const mismatchError = new Error(
	`Mismatched API response and Header unique number (${apiData.uniqueNumber || 'null'} and ${uniqueNumber})`,
	)
	const logger: Logger = Logger.getInstance()
	logger.log('error', mismatchError, 'Unexpected API gateway response')
	throw mismatchError
	}

[rocketnova]

Therefore, I think you should either not include the nullResponseShort or handle the mismatchError first before you handle the new null response error.

[lomky]

oh interesting - I was considering mismatched UniqueNumber when the API gave us a null to be incidentally catching the null response case, and that this is a more accurate error for that situation. That is still reachable if we get back the different unique number, or get back some claim data but a null unique number.

[rocketnova]

Oh interesting. I see what you mean. This sounds good to me!

[rocketnova]

This is neat

[rocketnova]

I feel like hard coding these "null" responses is not the right way to approach this, but I think that #150 is actually the right way, so this seems like a good enough approach until we get #150 done.

[rocketnova]

One minor nit. LGTM!