[Error handling] Evaluate MCAD code base for better error handling

[asm582]

WHY

This change is needed to retry or appropriately update etcd

WHAT

Review code base for error handling scenarios

HOW

Make relevant code changes and print appropriate error strings.

TESTS

Write additional tests for error handling

DONE

Increase in test cases that support error handling use case.

[Fiona-Waters]

Hi @asm582, just a question about this issue which I have started working on. Is it appropriate to update some functions to return errors, so that we can catch the errors when the functions are called or do we just want to add logging of errors for other function calls inside the functions? I just don't want to many any changes that could effect others using MCAD if that's not what is required. Please let me know what you think. Thank you.

[asm582]

Hi @Fiona-Waters , I think it's a good idea to start logging errors for now and then we can design later how we can gracefully handle errors.