add playwright test for no JS errors on TOC

tests/integration/playwright/tests/html-toc-js.spec.ts

@@ -0,0 +1,14 @@
+import { expect, Page, test } from "@playwright/test";
+
+const testPages = {
+  'posts': 'table.html',
+};
+
+test("toc navigation doesn't crash", async ({ page }) => {
+  const messages: string[] = [];
+  page.on('pageerror', (error) => {
+    messages.push(`[${error.name}] ${error.message}`);
+  });
+  await page.goto('./blog/simple-blog/_site/posts/post-with-code/index.html');
+  expect(messages).toStrictEqual([]); 
+});