wrap openid-config request in try/catch

server/fxa.js

@@ -9,6 +9,7 @@ async function getFxaConfig() {
   if (fxaConfig && Date.now() - lastConfigRefresh < 1000 * 60 * 5) {
     return fxaConfig;
   }
+  try {
     const res = await fetch(
       `${config.fxa_url}/.well-known/openid-configuration`,
       { timeout: 3000 }
@@ -16,6 +17,9 @@ async function getFxaConfig() {
     fxaConfig = await res.json();
     fxaConfig.key_scope = KEY_SCOPE;
     lastConfigRefresh = Date.now();
+  } catch (e) {
+    // continue with previous fxaConfig
+  }
   return fxaConfig;
 }