Use of $$props in component causing DOMException

[reinink]

I am using {...$$props} to unpack all the props applied to a <Link> component (to make it easier to apply other attributes, such as class names, styles, etc), and this is causing an odd bug.

When used in conjunction with a <Layout> component that has a slot, and a form input, when you change the form input value, it throw this error:

VM34:100 Uncaught (in promise) DOMException: Failed to execute 'setAttribute' on 'Element': '$$scope' is not a valid attribute name.
    at attr (eval at handle_message (about:srcdoc:68:8), <anonymous>:100:13)
    at set_attributes (eval at handle_message (about:srcdoc:68:8), <anonymous>:110:5)
    at Object.update [as p] (eval at handle_message (about:srcdoc:68:8), <anonymous>:418:5)
    at update (eval at handle_message (about:srcdoc:68:8), <anonymous>:182:16)
    at flush (eval at handle_message (about:srcdoc:68:8), <anonymous>:152:5)

It's odd, since the form input obviously has no connection to the <Link> components.

You can find a REPL of this issue here. Simply open up devtools, type something into the input, and you'll see the error.

Version: Svelte 3.0.0
Browser: Chrome 73.0.3683.103 (Official Build) (64-bit)

[EmilTholin]

Having an input in a slot seems to add the $$scope to the $$props of the component with the slot when the input value changes (REPL).

[EmilTholin]

Changing the div in my linked REPL above to <div {...$$props} />, the fragment change handler looks like this:

p(changed, ctx) {
  // ...

  set_attributes(div, get_spread_update(div_levels, [
    (changed.$$props) && ctx.$$props
  ]));
},

Maybe the $$scope property of the $$props object could be discarded in set_attributes?

export function set_attributes(node, attributes) {
  for (const key in attributes) {
    if (key === 'style') {
      node.style.cssText = attributes[key];
    } else if (key in node) {
      node[key] = attributes[key];
-   } else {
+   } else if (key !== '$$scope') {
      attr(node, key, attributes[key]);
    }
  }
}

Or possibly taken care of in get_spread_update instead?