Error when generating client token (PayPal and Firebase Functions)

Question

Here is the code I am trying to deploy:

exports.generateToken = functions.https.onRequest((request, response) => {
    gateway.clientToken.generate({ }, function (err, response) {
        var clientToken = response.clientToken;
        response.send(clientToken);
    });
});

And this is the error message generated during deploy:

  10:36  error    Expected error to be handled    handle-callback-err
  10:36  warning  Unexpected function expression  prefer-arrow-callback

Any help on how to fix this?

Answer 1

Missing error handling was causing the issue. After adding the following lines, I was able to deploy successfully:

exports.generateToken = functions.https.onRequest((request, response) => {
    gateway.clientToken.generate({ }, function (err, response) {
        // error has to be handled
        if(err) {
           // handle error here
        } else {
           var clientToken = response.clientToken;
           response.send(clientToken);
        }
    });
});

Additional info is here.