Improve error handling and xref support

Malformed links could break the "preserve query string" function which could in turn stop querystring replacement for most of the page

Catches any error attempted to replace querystring elements in a link and logs as an error

To minimize errors, query string replacement on links is done *before* attempting to preserve query strings

xrefs (of type a.page) automatically have querystring preserved in their links

preview-src/index.adoc

@@ -56,6 +56,9 @@ And this also should not: [.no-query-replace]`%USER%`
 
 You should see USER replacement here: %USER% but not here: [.no-query-replace]#%USER%#
 
+=== Xrefs
+
+xref:index.adoc#link-testing[This,role="page"] is an xref that needs the query string preserved.
 
 == Cu solet
 

src/js/07-userparams-behaviour.js

@@ -3,12 +3,17 @@ document.addEventListener('DOMContentLoaded', function () {
   // If there is a query string, we need to fix up the page to make sure the query string is properly preserved
   var desiredQueryString = new URLSearchParams(window.location.search)
   if (desiredQueryString.toString()) {
-    preserveQueryString(desiredQueryString)
+
     // If there are query parameters (searchparams) in the current window location
     // then iterate over all them replacing text and link-hrefs that contain them
     for (var k of desiredQueryString.keys()) {
       replaceParamsInNodes(document.body, k, desiredQueryString.get(k))
     }
+
+    // NOTE: Once all links have been query string replaced, then attempt to preserve the query string
+    // for all references
+    preserveQueryString(desiredQueryString)
+
   }
 
   function preserveQueryString (desiredQueryString) {
@@ -23,17 +28,27 @@ document.addEventListener('DOMContentLoaded', function () {
     if (paramLinks) {
       paramLinks.forEach(appendQueryStringToHref)
     }
+
+    // Handle xrefs, which are anchor elements generated by antora with the page attribute
+    var xrefLinks = document.querySelectorAll('a.page')
+    if (xrefLinks) {
+      xrefLinks.forEach(appendQueryStringToHref)
+    }
   }
 
   function appendQueryStringToHref (el) {
     // NOTE: desiredQueryString captured from above
     if (desiredQueryString.toString()) {
-      var hrefURL = new URL(el.href)
-      for (var k of desiredQueryString.keys()) {
-        hrefURL.searchParams.set(k, desiredQueryString.get(k))
-      }
+      try {
+        var hrefURL = new URL(el.href)
+        for (var k of desiredQueryString.keys()) {
+          hrefURL.searchParams.set(k, desiredQueryString.get(k))
+        }
 
-      el.href = hrefURL.toString()
+        el.href = hrefURL.toString()
+      } catch (err) {
+        console.error('Unable to append query string to element [' + el.innerHTML + ']: ' + err)
+      }
     }
   }