fix: json error formatter when files are empty

[shyim]

Hey,

I am trying to parse the JSON output of PHPStan in Go.

When it is filled I get:

"files: { "filename.php": {}}

but when not it's

"files": []

so it changes it type from object to array and it explodes in another languages like Go:

Error: json: cannot unmarshal array into Go struct field PhpStanOutput.files of type map[string]struct { Errors int "json:\"errors\""; Messages []struct { Message string "json:\"message\""; Line int "json:\"line\""; Ignorable bool "json:\"ignorable\""; Identifier string "json:\"identifier\"" } "json:\"messages\"" }

[ondrejmirtes]

You could even go further and make everything that's string-indexed array here being encoded into stdClass. But I don't require that.