Move html attribute to onRenderBody

Author: Ailrun

Diff for: gatsby-ssr.ts

@@ -1,7 +1,9 @@
 import importedOnPreRenderHTML from './gatsby/onPreRenderHTML';
+import importedOnRenderBody from './gatsby/onRenderBody';
 import importedWrapPageElement from './gatsby/wrapPageElement';
 import importedWrapRootElement from './gatsby/wrapRootElement';
 
 export const onPreRenderHTML = importedOnPreRenderHTML;
+export const onRenderBody = importedOnRenderBody;
 export const wrapPageElement = importedWrapPageElement;
 export const wrapRootElement = importedWrapRootElement;

Diff for: gatsby/onRenderBody.tsx

@@ -0,0 +1,9 @@
+import type { RenderBodyArgs } from 'gatsby';
+import { languageToBCP47, locationToLanguage } from '../src/utils/languages';
+
+const onRenderBody = ({ pathname, setHtmlAttributes }: RenderBodyArgs): void => {
+  setHtmlAttributes({
+    lang: languageToBCP47(locationToLanguage({ pathname })),
+  });
+};
+export default onRenderBody;