Postman, tips to secure test does not fail due to unexpected response

Earlier today I had an issue where my tests would fail in case the service went down, the response would be in HTML format and since I parsed the response data and checked the values, my tests would fail.

I have fixed this by adding a response header check, where I make sure the Content-Type received is application/json.

What would be things to check for to attempt and make sure issues such as this do not fail my tests?

Does anyone have any tips for me?

I have additional questions.
Should I always make sure the parameter I am attempting to save as a variable exists in the response?

Thank you!

I am open to any tips/examples in case you can provide some.