Improve sip API error handling

unfurler/src/routes.ts

@@ -1,5 +1,17 @@
 import fetch from 'node-fetch-commonjs';
 import config from './config';
+import http from 'node:http';
+import https from 'node:https';
+
+const httpAgent = new http.Agent({ keepAlive: true });
+const httpsAgent = new https.Agent({ keepAlive: true });
+const agentSelector = function(_parsedURL: any) {
+    if (_parsedURL.protocol == 'http:') {
+        return httpAgent;
+    } else {
+        return httpsAgent;
+    }
+}
 
 interface Match {
   render: boolean;
@@ -16,6 +28,15 @@ interface SipTemplate {
   getData: Function;
 }
 
+async function sipFetchJSON(url, defaultVal = null) {
+  try {
+    const response = await fetch(url, { agent: agentSelector });
+    return response.ok ? response.json() : defaultVal;
+  } catch (error) {
+    return defaultVal;
+  }
+}
+
 const routes = {
   about: {
     title: "About",
@@ -41,11 +62,11 @@ const routes = {
         if (params?.length) {
           let blockId = params[0];
           if (blockId.length !== 64) {
-            blockId = await (await fetch(config.API.ESPLORA + `/block-height/${blockId}`)).text();
+            blockId = await (await fetch(config.API.ESPLORA + `/block-height/${blockId}`, { agent: agentSelector })).text();
           }
           const [block, transactions] = await Promise.all([
-            (await fetch(config.API.MEMPOOL + `/block/${blockId}`)).json(),
-            (await fetch(config.API.ESPLORA + `/block/${blockId}/txids`)).json()
+            sipFetchJSON(config.API.MEMPOOL + `/block/${blockId}`),
+            sipFetchJSON(config.API.ESPLORA + `/block/${blockId}/txids`),
           ])
           return {
             block,

unfurler/views/block.ejs

@@ -79,12 +79,14 @@
           <td><%= data.block.merkle_root %></td>
         </tr>
       </table>
+      <% if (data.transactions) { %>
         <h2><%= data.transactions.length %> Transactions</h2>
         <ol>
           <% data.transactions.forEach((txid, i) => { %>
             <li><a href="/tx/<%= txid %>"><%= txid %></a><% if (i === 0) { %> (Coinbase)<% } %></li>
           <% }); %>
         </ol>
+      <% } %>
     </div>
     <%- include('footer'); %>
   </body>

unfurler/views/footer.ejs

@@ -1,3 +1,4 @@
+<br><hr><br>
 <app-global-footer>
   <footer>
     <div class="container-fluid">