Undefined property: stdClass::$id error - php

Question

I'm trying to add an imagename and imagepath records to a mysql database whenever i upload a new picture, however, I am getting the following errors:
undefined property: stdClass::$id in C:\Service\ChallengeService.php on line 184
undefined property: stdClass::$id in C:\Service\ChallengeService.php on line 188
I replicated a function which also saves images in the same fashion to the similar fields and i pretty much just reused the function so i don't know why its giving me an error.
This is the function that updates my database:
public function updateChallengeImage($challenge) {
try {
$query = "update challenges
set image = :image
,image_file_name = :image_file_name
where
id = :id";
$values = array(
":image" => $challenge->image,
":image_file_name" => $challenge->image_file_name,
":id" => $challenge->id
);
$stmt = $this->db->prepare($query);
$stmt->execute($values);
return $challenge->id;
} catch (PDOException $e) {
$this->logger->error("PDO: ".$e->getMessage(), ["class"=>get_class($this),"method"=>__METHOD__]);
return -1;
}
}
Why isn't the $id variable being passed on? I also have this warning popping up in my logs:
PHP:WARNING Creating default object from empty value in `C:\\classes\napify\Controller\ChallengesController.php on line 106`
However my controller function looks fine, its supposed to load the ID from the database:
public function saveChallengeImage($request, $response, $args) {
$files = $request->getUploadedFiles();
$data = $request->getParsedBody();
$valid = true;
if (!(Utils::isImage($files['image']->file))) {
$this->flash->addMessage('message', 'Las imagenes no deben superar los 700kb ');
$this->flash->addMessage('error', 1);
$valid = false;
}
if ($valid) {
$challenge = $this->ChallengeService->getChallenge(filter_var($data['challenge_id'], FILTER_SANITIZE_STRING));
$challenge->image_file_name = $files['image']->getClientFileName();
$challenge->image = $this->saveFile($files['image']);
$this->ChallengeService->updateChallengeImage($challenge);
$this->flash->addMessage('message', 'Se guardó la imagen.');
}
The getChallenge function that is being called on the controller.
public function getChallenge($id) {
try {
$query = "select
c.id
,c.title
,c.description
,c.active
,c.start_date
,c.end_date
,c.image
,c.image_file_name
,c.color1
,c.color2
,c.color3
,c.color4
from
challenges c
where
id = :id";
$values = array(
":id" => $id
);
$stmt = $this->db->prepare($query);
$stmt->execute($values);
$stmt->setFetchMode(PDO::FETCH_CLASS, 'napify\Model\Challenge');
return $stmt->fetch();
} catch (PDOException $e) {
$this->logger->error("PDO: ".$e->getMessage(), ["class"=>get_class($this),"method"=>__METHOD__]);
return null;
}
}
I am uncertain as to why its failing to either load the ID from the database or failing to update the database with the imagefile and imagename values. Any help that points me in the right direction or that can tell me where am i making mistakes is appreciated.