Fixes #1538, where I recommended that people do async setup work in src/hooks.js (or any other module, really) using top-level await. This works wonderfully in development, but it turns out svelte-kit build fails because Vite runs everything through esbuild (not sure why, if I'm perfectly honest, but that's a separate conversation) and we currently use target: 'es2020' which doesn't allow top-level await:

chunks/hooks-4fb5bb73.js:206:0: ERROR: Top-level await is not available in the configured target environment ("es2020")

This changes it to node16. I tried node14 at first, but that still didn't work even though top-level await definitely is supported there. I think this is probably fine, and at any rate, you can override it in config.kit.vite.build.target.

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