Add error output on http service get

api/routes/slotting.js

@@ -38,6 +38,10 @@ const getHtml = (options, onResult) => {
         onResult(res.statusCode, output);
       }
     });
+
+    res.on('error', (err) => {
+      onResult(500, err);
+    });
   });
   req.end();
 };