ERROR:flutter/lib/ui/ui_dart_state.cc(209) instead of response.statusCode == 404
the urlString you used is not working.The urlString will be : https://samples.openweathermap.org/ this one is working.
Try to change your url from :
http://Qsamples.openweathermap.org/
To :
http://samples.openweathermap.org/q
it should return 404 error