[FW-1706] Refactoring of various error-related matters on SF

[sebaholesz]

Q	A
Description, reason for the PR	This PR mainly aims to improve how we work with status codes and how we understand error handling.
New feature	No
BC breaks	No
Fixes issues	...
Have you read and signed our License Agreement for contributions?	Yes

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🌐 Live Preview:

• https://sh-serverside-error-codes.odin.shopsys.cloud
• https://cz.sh-serverside-error-codes.odin.shopsys.cloud

[vitek-rostislav]

Feedback from testing:

• resolve-friendly-url script can hypothetically return any return code so I suggest taking this into account in middleware.ts - I would respect the returned code and pass it in MIDDLEWARE_STATUS_CODE_KEY. For 4XX codes, it can still return the message 'Friendly URL page not found'
• middleware.ts - It is not safe to pass the JSON.stringify(e) in the MIDDLEWARE_STATUS_MESSAGE_KEY header as it might expose sensitive data. I would rather use the logException function.
• middleware.ts - the JSON.stringify(e) piece of code mentioned above does not work as expected - in the logs, I see just Middleware runtime error ({}}) - but this should be probably resolved by the point above
• It would be nice to describe the logException function in the documentation and motivate developers to use it

[vitek-rostislav]

Hi, @sebaholesz, thanks for the fixes 👌 I noticed one more thing that might be addressed (but I do not insist on that, I suggest you discuss this with @pk16011990. We have the following code in _error.tsx:

const ErrorPage: NextPage<ErrorPageProps> = ({ hasGetInitialPropsRun, err, statusCode }): ReactElement => {
    if (!hasGetInitialPropsRun && err) {
        logException(err);
    }

    return statusCode === 404 ? <Error404Content /> : <Error500Content />;
};

That means, even 410 errors (which now can be returned from the middleware) will be rendered as 500 error page. So the page currently looks like this:

It is essential to mention that the HTTP code is correctly set to 410.
For me, a good enough solution would be:

- return statusCode === 404 ? <Error404Content /> : <Error500Content />;
+ const notFoundStatusCodes = [404, 410];
    
+ return notFoundStatusCodes.includes(statusCode) ? <Error404Content /> : <Error500Content />;

However, the question is, what about the other status codes, do we want to care about them? 🙂

[pk16011990]

missing upgrade notes