Handle json parsing exception for system alerts

[ciaranschutte]

Description of changes

handles JSON parsing exceptions when getting local storage
fixes infinite loop when exception is thrown with no item found: JSON.parse('') '' is not a valid JSON string
additionally checks if parsed value is array as expected by the component

Type of Change

• Bug
• Dependency updates
• Feature
• Refactoring
• Release candidate
• Styling
• Testing
• Other (please describe)

Checklist before requesting review

• Design (select one):
  • Matches design:
    • component sizes, spacing, and styles
    • font size, weight, colour
    • spelling has been double checked
  • No design provided, screenshot of changes included in PR
  • No changes to UI
• Back-end (select one):
  • Back-end PRs merged, tested on develop, and linked in this PR
  • No back-end changes
• Manually tested changes
• Added copyrights to new files
• Connected ticket to PR