Parser unexpected behavior on value-less attribute

[pushkine]

https://astexplorer.net/#/gist/2bbf556514bd54e799f8b9c836f6b7c9/3896519c24f22c47c49059def15ffed41c709c82

<div foo= ></div>

{
  "start": 5,
  "end": 10,
  "type": "Attribute",
  "name": "foo",
  "value": []
}

Unexpected "value": [], value is undefined.
Expected either Parser Error or "value": true (html behavior)

[pngwn]

While browsers will repair this, it is invalid. I think this should be a parser error.

[unlocomqx]

It's invalid html according to W3C Validator

Error: Attribute value missing.

[Conduitry]

The parser returns a more helpful "Expected value for the attribute (1:10)" error now in 3.42.0.