alias: handle 304

lib/alias.js

@@ -204,6 +204,11 @@ export default class Alias extends Now {
         }
       });
 
+      if (304 === res.status) {
+        console.log('> Certificate already issued.');
+        return;
+      }
+
       const body = await res.json();
       if (this._debug) console.timeEnd(`> [debug] /certs #${attempt}`);