fix: call all event handlers even if an exception occurs in one

[adiguba]

Error in Svelte event dispatcher is inconsistant with the browser event handling.

I think that Svelte should mimic the browser event handling : if an error occurs on an event-handler, it should be stopped, but it should not impact the others event-handlers.

Fixes https://github.com/sveltejs/svelte/issues/8403

Note that I try to write an unit-test, but it fails because of the exception on the handler, and I don't know how to ignore that.

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• [X] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• [X] Prefix your PR title with feat:, fix:, chore:, or docs:.
• [X] This message body should clearly illustrate what problems it solves.
• [ ] Ideally, include a test that fails without this PR but passes with it.

Tests

• [X] Run the tests with npm test and lint the project with npm run lint

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[Rich-Harris]

Closing as we're no longer adding stuff to Svelte 4, but updated #8403 for Svelte 5