append_styles s/b typed as an optional parameter in function init(...)

[stemcstudio]

Describe the bug

If the generated JavaScript code (for the simplest Hello World case) is given a .ts extension and analyzed by the TypeScript compiler, the error is "Expected 7-8 arguments, but got 6." This is because the current prototype of the init function in Component.ts requires append_styles.

Reproduction

You can see this in my STEMCstudio browser-based application (an online coding environment for education that supports Svelt).

https://stemcstudio.com/gists/078c883495d81d6976ae798c9e243b76

Selecting the "Workspace Settings" menu (cog wheel) and the "Show Intermediate (TypeScript) Code" menu item shows that the call to init has six arguments. The append_styles parameter is not required (as evidence in the Svelt source code).

The fix would be to change the append_styles type in src/runtime/internal/Component.ts to something like:

append_styles?: (root: Element | ShadowRoot) => void,

OR

append_styles?: (root: Node) => void

I'm not quite sure which is best or what the intent is.

I can make a recommendation if rectifying this issue is given favorable consideration.

Logs

No response

System Info

Version 3.46.3 of Svelte and below.

Severity

annoyance