Minor frontend fixes to improve unit test reliability

[molly-moen]

In our testing of the feasibility of upgrading to react-16.13 a few unit tests failed due to the new version being stricter about catching errors. These fixes will prevent some tests from failing when we upgrade.
The fixes are:

• instead of using && to set a title field, use ternary and assign to undefined if the expression would have evaluated to false
• only call .empty in unit tests on lists (was calling on a non-existent state variable and on 0 before)
• check for the existence of an object before trying to get an element out of it (this caused occasional failures already).

Testing story

Tested these by running unit tests and verifying they still pass on our current react version, and will pass if we upgrade to > React 16.

Reviewer Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked