Add headers

src/pages-service.js

···
     if (this.verbose) {
       console.log(`Fetching ${url}`);
     }
-    const res = await fetch(url);
+    const res = await fetch(url, {
+      headers: {
+        Accept: "application/json",
+      },
+    });
     const blob = await res.json();
     const content = blob.contents;
     this.fileCache.set(filename, content);