Prestashop module review - Edge case improvements

[BitcoinMitchell]

Description

General fixes based on the feedback from the Prestashop Module team. There are still a lot of edge-cases that I hadn't found, didn't test, etc.

This resolves quite a few of them.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change which improves the codebase)

How Has This Been Tested?

Test Configuration:

• BTCPay Server version: v1.13
• PrestaShop version: 8.1.0
• PHP version: 8.1.22

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have checked my code and corrected any misspellings

[ndeet]

Works and LGTM!