feat(sveltekit): Add wrapper for server load function

[AbhiPrasad]

closes #7403

Add wrapper for server-side load function.

Also went ahead and fixed the mechanism type to be instrument, since sveltekit is not an accepted value. Nvm I misunderstood, changed this decision.

Using Proxy for this which I assume is fine, but we can avoid using it if needed

Usage:

src/routes/blog/[slug]/+layout.server.js

import * as db from '$lib/server/database';
 
/** @type {import('./$types').LayoutServerLoad} */
async function customLoad() {
  return {
    posts: await db.getPostSummaries()
  };
}

export const load = wrapLoadWithSentry(customLoad);

We also special case errors coming from the SvelteKit error helper.

If users defined a load function like so:

import { error } from '@sveltejs/kit';
import * as db from '$lib/server/database';
 
/** @type {import('./$types').PageServerLoad} */
export async function load({ params }) {
  const post = await db.getPost(params.slug);
 
  if (!post) {
    throw error(404, {
      message: 'Not found'
    });
  }
 
  return { post };
}

We would not capture that thrown error as it is a 404. In the future we can provide a way to opt-in to 4xx errors.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	20.39 KB (-0.05% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	63.24 KB (-0.05% 🔽)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.96 KB (-0.09% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	56.15 KB (-0.06% 🔽)
@sentry/browser - Webpack (gzipped + minified)	20.63 KB (-0.06% 🔽)
@sentry/browser - Webpack (minified)	67.38 KB (-0.05% 🔽)
@sentry/react - Webpack (gzipped + minified)	20.65 KB (-0.06% 🔽)
@sentry/nextjs Client - Webpack (gzipped + minified)	52.05 KB (-0.02% 🔽)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	33.63 KB (-0.03% 🔽)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	25.98 KB (-0.07% 🔽)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	43.18 KB (+0.01% 🔺)
@sentry/replay - Webpack (gzipped + minified)	37.19 KB (0%)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	61.28 KB (-0.03% 🔽)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	54.36 KB (-0.03% 🔽)

[mydea]

should we do the same here as we just fixed in next, return the original promise, and do the capturing of errors separately?

[mydea]

see: #7456

[AbhiPrasad]

this is freaking cursed that this is even a possibility LOL

but yes we should 😞