Errors on order page BO in PS8

[mark-app]

Module version

1.8.2

PrestaShop version

8.1.1

PHP version

8.1.1

What went wrong?

If I want to see the order page in the Backoffice I get an 500 error. After enable debug mode i got the error:

Non-static method Gett\MyparcelNL\Service\WeightService::convertToGrams() cannot be called statically

Reproduction steps

1. Install the module
2. Navigate to the orders page

Relevant log output

No response

Additional context

[EdieLemoine]

Duplicate of #217