Having Error 3840 "JSON text did not start with array or object and option to allow fragments not set." after a while on the application

Question

I'm having the error 3840 "JSON text did not start with array or object and option to allow fragments not set." on my application after being on the same page for a while.

I'm calling a cloud code function from my Parse server, getting the answer and displaying it. It works fine, but after waiting a little bit the application crashes.

I'm calling my manager for the cloud code function:

ParseManager.sharedManager().fetchPrice(startDate: startDate, endDate: endDate, housingId: housing.objectId!) { (objects, error) in
    if (objects != []) {
        var price = 0

     for object in objects! {
         price += object["prix"] as! Int
     }
     price /= objects!.count
     self.priceByNight.text = "Price: \(price)"
    }
}

In my manager:

func fetchPrice(startDate: Date, endDate: Date, housingId: String, completion: PFResults?) {
 let params = [
    "startDate": startDate,
    "endDate": endDate,
    "housing": housingId
 ] as [String : Any]

 PFCloud.callFunction(inBackground: "fetchPrice", withParameters: params) { (objects, error) in
    if let error = error {
        print(error)
        completion?(nil, error)
        return
    }

    if let objects = objects as? [PFObject] {
        completion?(objects, nil)
    }
 }
}

This is what my function send me back:

{
    "result": [{
        "price": 10,
        "createdAt": "2019-05-07T12:39:47.320Z",
        "updatedAt": "2019-05-09T15:31:25.957Z",
        "date": {
            "__type": "Date",
            "iso": "2019-05-20T12:00:00.000Z"
        },
        "idHousing": {
            "__type": "Relation",
            "className": "myOtherClassName"
        },
        "objectId": "XXXXXXXXXX",
        "__type": "Object",
        "className": "MyClassName"
    }]
}

Answer 1

The problem was how I was checking what the manager was returning, checking it the wrong way made it try to do things with a null object.

The solution was to change if (objects != []) { to if let objs = objects { and it works now.