Undefined Array Key in Backend Module when using Site Sets

[d-g-codappix]

Bug Report

If a TYPO3 instance uses Site Sets, the ext_typoscript_setup.typoscript will be ignored (see: https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/ExtensionArchitecture/FileStructure/ExtTyposcriptSetupTyposcript.html)
The module configuration (settings) will be done by this file. Not consuming this file causes the missing configuration.

Expected behavior/output
I can see the backend module without any exception with correct price format.

Possible Solution
Move module configuration to pagets.typoscript.