Running PHP index without a `.env` setup fails with an unclear error

Start by running php index.php without a .env file to reproduce the failure. Read index.php and src/model/APNSCredentials.php, especially the constructor call and the reported strlen() error. Done means missing credentials produce a clear message about the missing .env and how to set it up instead of the current TypeError.

Hey @jkmassel, as you know, I'm a PHP noob. So feel free to close this issue if what I'm saying doesn't make sense.

I'm tracking this as an issue rather than a Slack convo because it feels tidier. Also, it might be a chance for me to link a PR to this issue to practice fixing.

After cloning the repo and running Composer, I tried to run php index.php knowing that I had no credentials setup to see the kind of error I'd get. This is what happened

➜ php index.php                                                                                                     
=== Push Notification Server ===
PHP Fatal error:  Uncaught TypeError: strlen() expects parameter 1 to be string, bool given in /Users/gio/Developer/a8c/php-push/src/model/APNSCredentials.php:12
Stack trace:
#0 /Users/gio/Developer/a8c/php-push/index.php(7): APNSCredentials->__construct(false, false, false)
#1 {main}
  thrown in /Users/gio/Developer/a8c/php-push/src/model/APNSCredentials.php on line 12

Fatal error: Uncaught TypeError: strlen() expects parameter 1 to be string, bool given in /Users/gio/Developer/a8c/php-push/src/model/APNSCredentials.php:12
Stack trace:
#0 /Users/gio/Developer/a8c/php-push/index.php(7): APNSCredentials->__construct(false, false, false)
#1 {main}
  thrown in /Users/gio/Developer/a8c/php-push/src/model/APNSCredentials.php on line 12

What I would have expected was a message about the missing .env with info on how to set it up.

Granted, for the context of this application, handling as one-off basic task like setting app .env might be overkill. Still worth tracking, though, I think.