feat(pkg): error handling

lib/pkg.js

@@ -14,7 +14,7 @@ module.exports = {
         app = require('./app');
     },
     request: (path) =>
-        new Promise((resolve) => {
+        new Promise((resolve, reject) => {
             app.callback()(
                 {
                     url: path,
@@ -26,7 +26,12 @@ module.exports = {
                     setHeader: () => {},
                     removeHeader: () => {},
                     end: (data) => {
-                        resolve(JSON.parse(data));
+                        data = JSON.parse(data);
+                        if (data.error) {
+                            reject(data.error.message);
+                        } else {
+                            resolve(JSON.parse(data));
+                        }
                     },
                 }
             );