You does nothing wrong, this is an apple quality control. I met this phenomenon, and - if I remember well - if the structure of the device token was invalid, no push notification was delivered...
This cannot be done. There isn't a sure fire way to tell if a push notification was sent successfully or not. There are alternatives, but they are not on the fly and not as reliable.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.