also fall back to duckduckgo on in-text citations

accidentally missed this one the first time around

web/src/pages/index.tsx

@@ -88,9 +88,12 @@ const ShowCitation: React.FC<{citation: Citation, i: number}> = ({citation, i})
 };
 
 const ShowInTextCitation: React.FC<{citation: Citation, i: number}> = ({citation, i}) => {
+    const url = citation.url && citation.url !== ""
+                ? citation.url
+                : `https://duckduckgo.com/?q=${encodeURIComponent(citation.title)}`;
     return (
         <A className={Colours[i % Colours.length] + " border-2 rounded text-sm no-underline w-min px-0.5 pb-0.5 ml-1 mr-0.5"}
-            href={citation.url}>
+            href={url}>
             [{i + 1}]
         </A>
     );