Poor error handling when handling unexpected atomic test input.

[Spooky03]

Describe the bug
If an atomic test has not been configured correctly, atomic-operator will not handle it gracefully, and exit. This requires the user to modify the atomic tests folder in order to be able to use the package, which is frustrating and slow.

To Reproduce
Download the most recent atomic red team folder. Try to run a test, it will fail beacuse of many tests missing GUIDs. Ref

Expected behavior
Ignore Atomic tests that fail to be loaded when itializing an Atomic object (ref). Or, gracefully handle the error and exit. The former seems easier from an end user perspective.