Dart analyze emits extra output on JSON

[eli-amazing]

Hey there,
It seems that when you run analysis using the dart CLI and choosing output format JSON, you can't pipe it to a parser without cleaning the output a little

Running the command dart analyze . --format json
Would yield the following if there are no errors

Analyzing ....
No issues found!

If there are errors, this would yield

Analyzing ....
{JSON omitted for brevity}

A quick inspection into the command source led me to understand that it's already being done on machine output and it's unclear to me why not also on JSON

Thanks
Eli

[kzrnm]

The issue should have been fixed by #54877.