Getting the Status from a REST call

Hi Folks,
I’m having trouble getting a proper handling from Snaplogic on a REST call.

So the rest call will return on success:
“entity”:
{
“MessageId”:“0101017165ec422f-dfa2bb38-faac-4c48-bcd7-0e2869d80fb6-000000”, …}

And on Error:

“entity”: "ERROR: An error occurred …

Thing is these are different - one is a dictionary and the other a string. So it fails badly when I check for entity error.

Is there a standard pattern for this?

Thanks,
Tim