fix(w3c/headers): error when license is unknown (speced#3806)

src/w3c/headers.js

@@ -301,6 +301,15 @@ export async function run(conf) {
     const hint = docLink`Please set ${"[license]"} to "w3c-software-doc" instead.`;
     showError(msg, name, { hint });
   }
+  if (!licenses.has(conf.license)) {
+    const msg = `The license "\`${conf.license}\`" is not supported.`;
+    const choices = codedJoinOr(Array.from(licenses.keys()), {
+      quotes: true,
+    });
+    const hint = docLink`Please set
+      ${"[license]"} to one of: ${choices}.`;
+    showError(msg, name, { hint });
+  }
   conf.licenseInfo = licenses.get(conf.license);
   conf.isCGBG = cgbgStatus.includes(conf.specStatus);
   conf.isCGFinal = conf.isCGBG && conf.specStatus.endsWith("G-FINAL");

src/w3c/seo.js

@@ -91,7 +91,7 @@ async function addJSONLDInfo(conf, doc) {
     type,
     name: document.title,
     inLanguage: doc.documentElement.lang || "en",
-    license: conf.licenseInfo.url,
+    license: conf.licenseInfo?.url,
     datePublished: conf.dashDate,
     /** @type {{ name: string, url?: string } | { name: string, url?: string }[]} */
     copyrightHolder: {

tests/spec/w3c/headers-spec.js

@@ -1010,6 +1010,21 @@ describe("W3C — Headers", () => {
   });
 
   describe("license configuration", () => {
+    it("shows and error when the license is unknown", async () => {
+      const ops = makeStandardOps({
+        specStatus: "WD",
+        license: "document",
+        github: "w3c/respec",
+      });
+      const doc = await makeRSDoc(ops, simpleSpecURL);
+      expect(doc.respec.errors).toHaveSize(1);
+      const [error] = doc.respec.errors;
+      expect(error.plugin).toBe("w3c/headers");
+      expect(error.message).toContain(
+        'The license "`document`" is not supported.'
+      );
+    });
+
     it("defaults to cc-by when spec status is unofficial", async () => {
       const ops = makeStandardOps({
         shortName: "whatever",