Improve Psalm coverage for decoded datas from json files

[orklah]

As discussed here #525 I described some types to improve Psalm coverage from 98.9751% to 99.2148%

This is not very elegant but I don't see a better way without refactoring the code just to pass smaller chunks of the whole file.

[Ocramius]

Good improvement! Can you also update the baseline accordingly?

[orklah]

Good improvement! Can you also update the baseline accordingly?

Thanks! Nothing changes in the baseline when I launch the command. I think it's because I didn't add nor remove errors, just type coverage

[Ocramius]

Good as-is then 👍