feat: runtime dev warn for mismatched @html

[paoloricciuti]

Svelte 5 rewrite

My shot at closing #12362

I hope i did everything correctly and it seems to work but I'm obviously totally open to feedback.

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Latest commit: 49808f8

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[Rich-Harris]

Made a couple of tweaks:

• move the logic into a helper, modeled after the ones in client/dom/blocks. I'd like to move more server runtime logic into modules like these, since at the moment we have a lot of logic in one place
• added location information to make it easier to find the offending block
• removed the value from the warning. It's a nice idea, but HTML typically contains things like new lines, and there's really no way to reliably make it look good

[Rich-Harris]

thanks!

[paoloricciuti]

Made a couple of tweaks:

• move the logic into a helper, modeled after the ones in client/dom/blocks. I'd like to move more server runtime logic into modules like these, since at the moment we have a lot of logic in one place
• added location information to make it easier to find the offending block
• removed the value from the warning. It's a nice idea, but HTML typically contains things like new lines, and there's really no way to reliably make it look good

Great changes, thanks for the feedback! 🙏🏻