fix: allow dates after 1970 in range mode

[sahilrajthapa]

Describe your changes

Date-fns v4.1.0 treats null as 01/01/1970 (reference), which changes the behavior compared to previous versions. To maintain the same behavior as before, we can pass undefined instead of null. In this change, null is replaced with undefined while initializing parsedDateTwo.

Issue ticket number and link

Fixes #1082

Checklist before requesting a review

• I have performed a self-review of my code
• I have ensured that unit tests pass without errors
• If it is a new feature, I have added a new unit test