Error handling differences in server.js and page.server.js

[NoelJacob]

So,
expected errors in server.js -> return data with error
unexpected errors in server.js -> handleError in hooks.server.js
expected errors in page.server.js -> show +error.js
unexpected errors in page.server.js -> handleError in hooks.server.js

Am I right? This should be a table in docs I guess because it'll save a lot of debugging time.

[teemingc]

You’re right. To put it simply: if an error occurs during page rendering (load function / page / layout), Kit will render the nearest +error.svelte page.

However, if the error occurs in handle, an endpoint, or the root layout src/routes/+layout, it will return the fallback page src/error.html. This static html page ensures no further errors will be thrown.

Endpoints return json if the request’s accept header asks for it.

[NoelJacob]

How do I call the handleError for expected errors from an endpoint? Because the error is being thrown from an async function that is not awaited inside endpoint and that might be running even after endpoint function returns.

[teemingc]

You'll have to replicate the error handling logic in the endpoint itself. The handleError function does not handle endpoint thrown errors.