I have installed a Chrome dev editor tool, created a dart web app, and I unable to run it I get this error when I try to run it image
Then I tried to get the packages "Pub Get" and get this error image
I installed the dart via brew still the same.
I don't know what exactly causes your first error message but the 2nd is caused by an old Dart SDK version. Dart before about 1.8.0 isn't able to parse version constraints using the shorthand notation ^