Getting fatal error when adding array of struct into another array in swift

In my app i have a struct PlayerRegistrationModelArray. In which i have a variable player which is the array of another struct playerArray. I have created a variable of PlayerRegistrationModelArray in AppDelegate. But when i am trying to append playerArray into player in PlayerRegistrarionSecondViewController class i am getting error like:-

"Fatal error: Unexpectedly found nil while unwrapping an Optional value"

Please help me to solve the following issue.

struct PlayerRegistrationModelArray {
    var player: [playerArray]?
}

struct playerArray {
    var playerName: String
    var playerGender: String
    var playerDOB: String
    var playerSports: String
    var playerGrade: String
}




class AppDelegate: UIResponder, UIApplicationDelegate {

    var playerInfo: PlayerRegistrationModelArray?
}




class PlayerRegistrarionSecondViewController{

   var playerarr: playerArray?
 var mAppDelegate:AppDelegate = UIApplication.shared.delegate as! AppDelegate


func postAddPlayers(){

   playerarr = playerArray(playerName: name_TextField.text!, playerGender: gender_TextField.text!, playerDOB: dateOfBirth_TextField.text!, playerSports: sport_TextField.text!, playerGrade: grade_TextField.text!)

   var playerData = mAppDelegate.playerInfo?.player
   playerData?.append(playerarr!)
   if playerData!.count > 0 {
      print("DEBUG: playerData Is \(playerData!)")
   }

   for i in playerData! {
      paramters.updateValue(i.playerSports, forKey: "playerinfo[0][player_fullname")

}
}
}

When i am printing playerarr:

DEBUG: player array Is playerArray(playerName: "shy", playerGender: "Male", playerDOB: "1989-05-19", playerSports: "Baseball - 30 minute session", playerGrade: "5")