PHP 8.3 problems

[pysiek634]

Thank you for the usefull library.
There are a few problems on the latest version of PHP.

The first one blocks the operation of the whole software.

Warning: Attempt to read property "body" on false in /var/www/html/vendor/glushkovds/php-smpp/src/Client.php on line 518
see solution described in
onlinecity/php-smpp#104

There are also a few little problems when sending sms
Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /var/www/html/vendor/glushkovds/php-smpp/src/Client.php on line 740

Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /var/www/html/vendor/glushkovds/php-smpp/src/Transport/SMPPSocketTransport.php on line 23