`+error.svelte` needs to have a `load` function

Describe the problem

Previously error pages could have load functions, just like regular pages, from #5748 onwards that's no longer possible, the rationale given was that an error page doesn't really need a load function and a load function could potentially screw things up further.

But I think a very important and common scenario was overlooked: You might want to return data from the error page's load function that the layout will then consume, and just things of that nature in general.
So for instance:

error.ts:

export const load: ErrorLoad = () => {
    return {
        meta: {
            title: "404 Not Found",
            showFooter: false
        }
    };
};

This is actually very serious. I just realized there's no way of doing this right now, but it's needed in a lot of cases obviously. The current design doesn't provide any alternative.

Describe the proposed solution

Just allow error pages to have load functions like before please. You could then just simply point out in the docs that the load function of an error page must avoid doing anything that could potentially result in another error.

Alternatives considered

No response

Importance

i cannot use SvelteKit without it

Additional Information

No response

Start by tracing the error-page handling changed in #5748 and inspect how error.ts and its surrounding layout currently receive data. Done means an error page can export a load function, return data consumed by the layout, and avoid breaking existing error handling.