in term definition, the co-occurrence of `@language` and `@type` should be an error

Consider the following JSON-LD

{
    "@context": {
        "p": {
            "@id": "x:p",
            "@type": "x:datatype",
            "@language": "en"
        }
    },
    "p": "foo"
}

It expands to

[
  {
    "x:p": [
      {
        "@type": "x:datatype",
        "@value": "foo"
      }
    ]
  }
]

The @language is simply ignored.
This is the correct behaviour w.r.t. to the spec. Step 22 of the "Create Term Definition" algorithm explicitly instructs to ignore @language if @type is present.

I consider this as a bug in the spec. The context above makes no sense, and should be rejected with an invalid term definition error (at least, as of JSON-LD 1.2 -- we could preserve the current behaviour if mode is 1.0 or 1.1).

Start with the JSON-LD 1.1 API specification's Create Term Definition algorithm, especially step 22, and compare it with the supplied expansion example. Review the open discussion before deciding the intended version-specific behavior; done means the specification and its conformance expectations consistently address the co-occurrence of @language and @type.