- This is Microsoft.
- He returns Webhook success with a code 200 and plaintext 1.
- He returns Webhook failure with a code 200 and a string tells its endpoint returned error 400.
- the string didn't tell what exactly the error.
- Don’t be like Microsoft.
EDIT: Got a few details wrong since this happens a few months ago and this meme used to be on r/ProgrammerHumor. Also the proof: 
After working few years on a complex web application, I am starting to feel this style. Doing RESTful APIs for anything else than dead simple CRUD is pain.
It's similar to how I now often avoid throwing errors in my code, and instead return a 'results' object that could potentially have an error or a success. It often forces you to test and think about the non happy path more thoroughly.
Exceptions actually have a huge performance hit, you should only use them in a HALT EVERYTHING IMMEDIATELY situations and never in anything that could be called repeatedly. We have refactored few of those to be 10-100 times faster by just returning success: false instead of throwing and catching exceptions.