Adding a new IP failed after upgrading to php8.1.2

[Musonick58]

Describe the bug
After upgrading the server from php7.4.x to php8.1.2, I cannot add IPs to any subnet.

• phpIPAM version: [1.6.0]
• OS [Ubuntu 22.04.4 64bit]
• PHP version [php 8.1.2 64bit]
• Webserver [Apache]
• Database [mariadb Ver 15.1 Distrib 10.6.16-MariaDB]

Steps To Reproduce
Please include steps to reproduce the issue:

1. Go to a subnet e.g. '/index.php?page=subnets&section=1&subnetId=123'
2. Click on 'ADD new IP'
3. Compile the form
4. Click on '+ ADD IP'
5. See error

Screenshots and error logs
Warning: Undefined array key ptr in /var/www/phpipam/app/subnets/addresses/address-modify.php on line 211
Error: SQLSTATE[22007]: Invalid datetime format: 1366 Incorrect integer value: ' Warning: Undefined array key ' for column 'DBANME.ipaddresses.PTR at row 1'

Workaround
I've commented the file /var/www/phpipam/app/subnets/addresses/address-modify.php at line 211
and now I can save as usual.

[Musonick58]

Same as #4090

[linedpaper]

Having the same issue, also had to comment out line 474 in print-address-table.php