“Uncaught (in promise) undefined” error when using with=location in Facebook Graph API query

Question

I am currently developing a web application with the Facebook Graph API.

My current goal is to retrieve only posts which have a location attached.

While retrieving posts with and without location is already working, I am not able to retrieve only posts with location.

The query which retrieves both types looks like this: '/me/feed?fields=id,name,message,picture,place,with_tags&limit=100&with=location'

The query which should retrieve only posts with location looks like this: /me/feed?fields=id,name,message,picture,place,with_tags&limit=100&with=location

The problem I have is that with the parameter &with=location I get an error Uncaught (in promise) undefined at this part of my code:

if (response.paging && response.paging.next) {
    recursiveAPICall(response.paging.next);
  } else {
    resolve(postsArr);
  }
} else {
  // Error message comes from here
  reject();
}

Log shows the following:

DEBUG: -------------------------------
DEBUG: Ember             : 2.4.5
DEBUG: Ember Data        : 2.5.3
DEBUG: jQuery            : 2.2.4
DEBUG: Ember Simple Auth : 1.1.0
DEBUG: -------------------------------
Object {error: Object}
  error: Objectcode: 
    code: 1
    1fbtrace_id: "H5cXMe7TJIn"
    message: "An unknown error has occurred."
    type: "OAuthException"
    __proto__: Object
  __proto__: Object
Uncaught (in promise) undefined

Does anyone have a possible solution for this?

For further information how the code looks like see my previous question.

Answer 1

The error tells you that there is an error but you don´t catch it. This is how you can catch it:

getAllPosts().then(response => {
    console.log(response);
}).catch(e => {
    console.log(e);
});

You can also just put a console.log(reponse) at the beginning of your API callback function, there is definitely an error message from the Graph API in it.

More information: https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch

Or with async/await:

//some async function
try {
    let response = await getAllPosts();
} catch(e) {
    console.log(e);
}

Answer 2

The reject actually takes one parameter: that's the exception that occurred in your code that caused the promise to be rejected. So, when you call reject() the exception value is undefined, hence the "undefined" part in the error that you get.

You do not show the code that uses the promise, but I reckon it is something like this:

var promise = doSth();
promise.then(function() { doSthHere(); });

Try adding an empty failure call, like this:

promise.then(function() { doSthHere(); }, function() {});

This will prevent the error to appear.

However, I would consider calling reject only in case of an actual error, and also... having empty exception handlers isn't the best programming practice.