handle_event_propagation breaks due to fact that delegate is an array

[jurijzahn8019]

Describe the bug

Hi,

the change in this commit

https://github.com/sveltejs/svelte/pull/17030/files#diff-e0947e41d13f3575875c7158bc594ec03de070b6d687220f6ca84e23336f70eaR261

Breaks i a use case where

the event is added inside of a web component created with svelte >= v5.42.3
and also from another bundle which renders the webcomponent with svelte < 5.42.3 (propbably).

so something like this:

<my-element onclick={()=>console.log("hi")}>

Where "my-element" is a web-component created with svelte

In this case the call to

delegate.call()

breaks with error "delegate.call is not a function"

Reproduction

Create a webcomponent with latest svelte, which also binds a "click" event to its "host" element, and bundle it.
Create a svelte app which uses the webcomponent and use onclick to bind the event on the custom-element.

Click on the element

Error arises.

Logs

System Info

Latest Chrome, Edge, Firefox, Safari

Severity

blocking an upgrade

[dummdidumm]

Generally we don't support when things are compiled with multiple versions but this is exempt from that because it's compiled as a custom element.
I guess we need to make it a) backwards compatible somehow at least for Svelte 5 b) somehow mark delegated events of web components such that they don't partake in that delegation, or don't use event delegation at all in custom element builds

[jurijzahn8019]

We will definetely upgrade the version across all apps, but it takes time, so it would be cool, if the handling of event list could be returned for next 2-3 versions