Fix Error in ZAP for Alerts without Instances

[J12934]

Description

Encountered the following error in the ZAP parser when running a scan against BodgeIt:

Starting Parser
Fetching result file
Fetched result file
Parser failed with error:
TypeError: Cannot read property 'map' of undefined
    at createFindingFromAlert (/home/app/parser-wrapper/parser/parser.js:55:48)
    at parse (/home/app/parser-wrapper/parser/parser.js:96:23)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at async main (/home/app/parser-wrapper/parser-wrapper.js:126:16)

Update the test to test for this and updated the implementation.

Checklist

• Test your changes as thoroughly as possible before you commit them. Preferably, automate your test by unit/integration tests.
• Make sure npm test runs for the whole project.
• Make codeclimate checks happy