Completion Block Not Called When User Is Deleted - Firebase Swift

Question

I am having an error where when I delete my user information the completion block is not called. I have seen answers where the problem regards the completion block however my problem still persists. I am able to successfully delete the user from my database and I also re authenticate the user before deleting it. Here is my code:

let ref = FIRDatabase.database().reference()

let deleteUserFromCurrentSchool = ref.child("schoolOrWorkAddress").child(self.currentUser.schoolOrWorkAddress).child(self.currentUser.id)
deleteUserFromCurrentSchool.removeValue()

let deleteUserFromUserNode = ref.child("users").child(self.currentUser.id)
deleteUserFromUserNode.removeValue()

let currentUserToDelete = FIRAuth.auth()?.currentUser

if currentUserToDelete != nil {
    currentUserToDelete?.delete(completion: { (error) in
        if error != nil {
            ProgressHUD.showError(Constants.ProgressMessages.errorMessage)
        } else {
            ProgressHUD.showSuccess("Account Deleted. Thanks for using ZipShare!")
            let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Home")
            self.present(vc, animated: true, completion: nil)
        }
    })
}

As I was saying the user is being deleted. However the code after the completion block is not being called. I don't really know why and any help would be appreciated!

PS: Just to be clear here is the code not being called:

if error != nil {
    ProgressHUD.showError(Constants.ProgressMessages.errorMessage)
} else {
    ProgressHUD.showSuccess("Account Deleted. Thanks for using ZipShare!")
    let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Home")
    self.present(vc, animated: true, completion: nil)
}