[+] Fixed NPE on permission check
[+] Fixed plugin wouln't start on startup
[+] Rollback change from support 1.21.9 - 1.21.10 to 1.21.8

[+] Fixed NPE on permission check

[+] Fix unable to send commands
[+] Rework auto-sync task
[+] Added permission requirement on product just by adding permission: inside of shop-options:
[+] Added placeholder in the Shop Title
- {balance} - Raw Balance
- {balance_decimals} - Decimal Balance
- {balance_digits} - Balance Digits
- {balance_formatted} - Balance Formatted
[+] Added support for 1.21.9 - 1.21.10

[+] Added Auto Sync to make there are no delay and error on the synchronization.
[+] Added Sync Interval, Auto Save Interval on config.
[+] Added Discord Webhook configuration on config
[+] Added support to 1.21.8
[+] Remove support from 1.8 to 1.12
[+] Added Placeholder of player credits balance on Shop GUI

Fix up the default jar, the new one is actually support real-time multi-server synchronization.