According to the subprocess.check_output()
docs, the exception raised on error has an output
attribute that you can use to access the error details:
try:
subprocess.check_output(...)
except subprocess.CalledProcessError as e:
print(e.output)
You should then be able to analyse this string and parse the error details with the json
module:
if e.output.startswith('error: {'):
error = json.loads(e.output[7:]) # Skip "error: "
print(error['code'])
print(error['message'])