Fix unhandled promise rejection (#162)

lib/index.js

@@ -404,7 +404,7 @@ export default class Now extends EventEmitter {
   }
 
   getNameservers(domain) {
-    return new Promise(resolve => {
+    return new Promise((resolve, reject) => {
       let fallback = false
 
       this.retry(async (bail, attempt) => {
@@ -445,6 +445,8 @@ export default class Now extends EventEmitter {
           return ns.length
         })
         resolve(body)
+      }).catch(err => {
+        reject(err)
       })
     })
   }