Handling of expected errors thrown using SvelteKit API

[deronek]

Hi, I was trying to use this library but I'm having some problems getting consistent error handling in all possible cases.

In SvelteKit, we use built-in error function to "throw" (in SvelteKit 2, not explicitly) custom HttpError to initiate HTTP error handling on the framework side, to respond with a custom HTTP status code. As an example:

error(503, "Service is now unavailable")

However, in current implementation, the error will not be catched by this library and we will just send a response back. This is because:

• expected errors are not going through SvelteKit handleError hook, Docs
• implementation of instrumentHandle for handle hook does not catch this HttpError. When the event resolves, error was already handled by SvelteKIt, setting the status code and the message. res gets returned with Response. https://github.com/jill64/sentry-sveltekit-cloudflare/blob/e34b9516861517cf4f11f7935aad90609a3d4e0c/src/server/instrumentHandle.ts#L54-L56

I'm positive that it's not expected to be working this way, since we see a catch block in the same function: https://github.com/jill64/sentry-sveltekit-cloudflare/blob/e34b9516861517cf4f11f7935aad90609a3d4e0c/src/server/instrumentHandle.ts#L64-L68

And below code in sendErrorToSentry: https://github.com/jill64/sentry-sveltekit-cloudflare/blob/e34b9516861517cf4f11f7935aad90609a3d4e0c/src/server/sendErrorToSentry.ts#L10-L18

So in my analysis, I think it's not possible to have both automatic Sentry error handling (it's still possible to throw normal JavaScript Error, which will force status code 500) and custom status codes/response. Is this expected? Could you analyze the possibility of handling this condition in your library? I'm happy to help with the implementation.

[jill64]

Thanks for opening this issue!

The instrumentHandle.ts implementation mimics @sentry/javascript/sveltekit/src/server/handle.ts.

https://github.com/getsentry/sentry-javascript/blob/7383f8ab00d5cd534ed19e59a260e18d194c23c8/packages/sveltekit/src/server/handle.ts#L198-L200

Personally, I would like to see this library serve as a workaround until @sentry/javascript officially supports cloudflare, and eventually go back to @sentry/javascript.

Adding features is all well and good, but if we move too far away from the original, it will be difficult to go back to the official @sentry/javascript.

However, I do understand that such features are important for some people. If there are many similar comments from others, I would consider implementing it.

[deronek]

I understand and agree that it's best for this library to keep its implementation as close to @sentry/sveltekit.

It would obviously be preferable to get this behavior discussed and implemented in the latter library, but since I cannot use it in production (hosting on CF), it might not be feasible for me to do it in the near future.