feat(api-history): `isHtml(node)` type guard

https://github.com/electron/website/pull/594#discussion_r1678184944

scripts/tasks/preprocess-api-history.ts

@@ -9,6 +9,7 @@ import { readFile, writeFile } from 'fs/promises';
 import { fromHtml } from 'hast-util-from-html';
 import logger from '@docusaurus/logger';
 import { parse as parseYaml } from 'yaml';
+import { isHtml } from '@site/src/util/mdx-utils';
 
 const apiHistoryRegex = /<!--[\s\S]*?(```[\s\S]*?```)[\s\S]*?-->/;
 
@@ -48,12 +49,13 @@ function findPossibleApiHistoryBlocks(tree: Root) {
   visit(
     tree,
     (node: Node) =>
-      node.type === 'html' &&
+      isHtml(node) &&
       (node as LiteralString).value.includes('```') &&
       (node as LiteralString).value.toLowerCase().includes('yaml') &&
       (node as LiteralString).value.toLowerCase().includes('history'),
     (node) => {
-      codeBlocks.push(node as Html);
+      if (!isHtml(node)) return; // Should never happen, but TypeScript needs this check
+      codeBlocks.push(node);
     }
   );
 

src/util/mdx-utils.ts

@@ -7,6 +7,7 @@ import {
   Link,
   Definition,
   Code,
+  Html,
 } from 'mdast';
 import { MdxjsEsm } from 'mdast-util-mdxjs-esm';
 import { Node } from 'unist';
@@ -48,6 +49,10 @@ export function isText(node: PhrasingContent): node is Text {
   return node.type === 'text';
 }
 
+export function isHtml(node: Node): node is Html {
+  return node.type === 'html';
+}
+
 /**
  * Imports a component from `@site/src/components`.
  *