Fix broken Ward last chapter downloading

It's not clear when this started happening, but the "Next Chapter" link in Last 20.e6 no longer works.

lib/download.js

@@ -65,14 +65,21 @@ function getNextChapterURL(rawChapterDoc) {
   // - https://parahumans.wordpress.com/2012/04/21/sentinel-9-6/
   // So instead search for the first <a> within the main content area starting with "Next", trimmed.
 
+  let result = null;
   const aEls = rawChapterDoc.querySelectorAll(".entry-content a");
   for (let i = 0; i < aEls.length; ++i) {
     if (aEls[i].textContent.trim().startsWith("Next")) {
-      return aEls[i].href;
+      result = aEls[i].href;
+      break;
     }
   }
 
-  return null;
+  // Except, this doesn't always work, because the "Next Chapter" link in
+  // https://www.parahumans.net/2020/04/28/last-20-e6/ is just broken for some reason. We hard-code that.
+  if (result === "https://www.parahumans.net/?p=3365&preview=true") {
+    return "https://www.parahumans.net/2020/05/02/last-20-end/";
+  }
+  return result;
 }
 
 function getChapterTitle(rawChapterDoc) {

lib/substitutions.json

@@ -9128,7 +9128,7 @@
       "after": "cross the ocean"
     }
   ],
-  "https://www.parahumans.net/?p=3365&preview=true": [
+  "https://www.parahumans.net/2020/05/02/last-20-end/": [
     {
       "before": "saying dad had custody",
       "after": "saying Dad had custody"