Update to use HEAD

Also added `console.log` line to help debug any future errors

Fixes #1248

Author: jasonjoh

tests/validator.js

@@ -20,9 +20,10 @@ function validateJson (query, isValidJson) {
 
 async function validateLink (linkUrl) {
   try {
-    const response = await fetch(linkUrl);
+    const response = await fetch(linkUrl, { method: 'HEAD' });
     return response.ok;
   } catch (error) {
+    console.log(JSON.stringify(error, null, 2));
     return false;
   }
 }