fix: ensure handling of containerPointToLatLng returning invalid values is handled correctly

[JamesLMilner]

Description of Changes

Noticed at the codesprint - if containerPointToLatLng returned null or undefined the null value would not be returned

Link to Issue

No issue

PR Checklist

• [x] The PR title follows the conventional commit standard
• [ ] There is a associated GitHub issue
• [ ] If I have added significant code changes, there are relevant tests
• [ ] If there are behaviour changes these are documented