Description
Is your feature request related to a problem? Please describe.
It's irritating that html elements being rendered with attrs get stringified when the value being passed them is falsey. Specifically in the null | undefined | false case. Currently null and undefined act as expected (they just skip the attr), but false gets serialized as "false" which is actually truthy.
<a {href} {download}>Download</a>
Describe the solution you'd like
Treat false like undefined and null are currently. Warn when a non-string value is being automatically stringified for an html element. You almost never want [Object object] in your html. You almost never want the elements of your array indiscriminately joined with commas in your html.
Describe alternatives you've considered
I can easily fix this by using {download || undefined} but I'd really rather not.
How important is this feature to you?
I don't think it's important to me personally because the fix is easy. I do think it's a gotcha that could affect adoption.
Additional context
Link.svelte
<script>
export href;
export let download = false;
</script>
<a {href} {download}>Download</a>
Consumer.svelte
<script>
import Link from './Link.svelte'
</script>
<Link href='www.google.com'>Google</Link>
<Link href='https://www.youtube.com/watch?v=dQw4w9WgXcQ' download>Video</Link>
Above, the google link gets a download=false attr, and the video gets a download=true. In both cases they're considered download links. Even worse, passing download={false} still fails the same way.