- add test suite for generateBreadcrumb() itself (in order to cover a missing branch)
- minor lint fixes
- remove unnecessary import from set_breadcrumbs test

+ update test to return a more consistent falsey value (null)

- I'm creating a reusable useContext mock for shallow()ed enzyme components
+ add more documentation comments + examples

+ test new usecontext shallow mock

+ fix bonus bug

+ Update EngineOverview logic to account for issues found during tests :)
  - Move http to async/await syntax instead of promise syntax (works better with existing HttpServiceMock jest.fn()s)
  - hasValidData wasn't strict enough in type checking/object nest checking and was causing the app itself to crash (no bueno)

- missed adding this test during telemetry work
- switching to shallow and beforeAll reduces the test time from 5s to 4s!

+ minor refactors/updates

- mostly testing fallbacks or removing fallbacks in favor of strict type interface
- these are slightly obsessive so I'd also be fine ditching them if they aren't terribly valuable