html-to-pdf: work around minified application.{css,js}

When Hugo minifies resources, it attaches an `integrity` attribute. This
is usually very good! However, when we're trying to generate a `.pdf`
from a HTML file that contains hrefs that contain absolute paths, as we
do when deploying to GitHub Pages, we have to work around that by
re-routing the files. Combined with an `integrity` attribute, this will
fail, and there is no way around it other than editing out that
attribute.

So let's do just that.

Hacky, but works, and we can proceed activities that are substantially
more fun than battling well-intentioned-but-sometimes-really-unhelpful
security measures without escape hatches (there is no way to tell
Chromium that yes, this is intentional, but we need to ignore those
integrity checks in this context, thank you for your cooperation).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

script/html-to-pdf.js

@@ -47,6 +47,19 @@ const htmlToPDF = async (htmlPath, options) => {
     // this script runs before deployment, on a file:/// URL, where we need to
     // be a bit clever to give the browser the file it needs.
     const original = req.url()
+    if (original === htmlPathURL) {
+      // Work around rerouted `.css` and `.js` files... Symptom: "has an
+      // integrity attribute, but the resource requires the request to be CORS
+      // enabled to check the integrity, and it is not. The resource has been
+      // blocked because the integrity cannot be enforced."
+      const body =
+        fs.readFileSync(htmlPath, "utf-8")
+	  // strip out the `integrity="sha256-..."` attributes
+          .replace(/(\/application\.[^"/]+") integrity="sha256-[^"]+"/g, "$1")
+      await route.fulfill({ headers: { "Content-Type": "text/html" }, body })
+      return
+    }
+
     const url =
       original.startsWith(baseURLPrefix)
         ? original