Undefined variable $targetLanguage

[h-e-l-l-o-w-o-r-l-d]

After installing this extension, the following error shows up at the top right corner in the module:

PHP Warning: Undefined variable $targetLanguage in /var/www/typo3_web-dev1/public/typo3conf/ext/datamints_locallang_builder/Classes/Services/ManifestBuildService.php line 188

Also, no language files are shown. Reimport results in the same error.

What's wrong here?

TYPO3 11.5.36