Extbase LocalizationUtility error feedback and logic can be improved
Two things should be done:
1. Early return should be done if $key is empty (won't matter if $extensionName or others are passed in this case - empty key equals null return value)
2. Failure to format with vsprintf should output a gentle message about the translation failure which includes the original string and the number of arguments being passed for easy comparison of marker and parameter counts.