better error message for old-style biblios (#451)

Author: bakkot

src/Spec.ts

@@ -1331,6 +1331,13 @@ ${this.opts.multipage ? `<li><span>Navigate to/from multipage</span><code>m</cod
     );
     const biblios = biblioContents.flatMap(c => JSON.parse(c) as ExportedBiblio | ExportedBiblio[]);
     for (const biblio of biblios.concat(this.opts.extraBiblios ?? [])) {
+      if (biblio?.entries == null) {
+        let message = Object.keys(biblio ?? {}).some(k => k.startsWith('http'))
+          ? 'This is an old-style biblio.'
+          : 'Biblio does not appear to be in the correct format, are you using an old-style biblio?';
+        message += ' You will need to update it to work with versions of ecmarkup >= 12.0.0.';
+        throw new Error(message);
+      }
       this.biblio.addExternalBiblio(biblio);
       for (const entry of biblio.entries) {
         if (entry.type === 'op' && entry.effects?.length > 0) {

test/errors.js

@@ -464,7 +464,6 @@ ${M}      </pre>
       }
     };
     await emu.build('foo/index.html', fetch, {
-      ecma262Biblio: false,
       copyright: false,
       warn: e =>
         warnings.push({
@@ -939,6 +938,16 @@ ${M}      </pre>
     );
   });
 
+  it('old-style biblio', async () => {
+    await assert.rejects(async () => {
+      const fetch = () => '';
+      await emu.build('index.html', fetch, {
+        copyright: false,
+        extraBiblios: [{ 'https://tc39.es/ecma262/': [] }],
+      });
+    }, /old-style biblio/);
+  });
+
   describe('SDO defined over unknown production', () => {
     it('unknown production', async () => {
       await assertError(

test/utils.js

@@ -34,7 +34,6 @@ async function assertError(obj, { ruleId, nodeType, message }, opts) {
   let rootFile = 'test-example.emu';
   if (opts?.asImport !== 'only') {
     await emu.build(rootFile, async () => html, {
-      ecma262Biblio: false,
       copyright: false,
       warn: e =>
         warnings.push({
@@ -72,7 +71,6 @@ async function assertError(obj, { ruleId, nodeType, message }, opts) {
   let importWrapper = `<emu-import href="./import.emu"></emu-import>`;
   let fetch = name => (name === rootFile ? importWrapper : html);
   await emu.build(rootFile, fetch, {
-    ecma262Biblio: false,
     copyright: false,
     warn: e =>
       warnings.push({
@@ -113,7 +111,6 @@ async function assertErrorFree(html, opts) {
   let warnings = [];
 
   await emu.build('test-example.emu', async () => html, {
-    ecma262Biblio: false,
     copyright: false,
     warn: e => warnings.push(e),
     ...opts,