No exception handling for invalid dates for the addhist function

[nus-pe-script]

Describe the bug
inputting an invalid date will cause the application to stall and return a result
To Reproduce
Steps to reproduce the behavior:
enter an invalid date after the hsd tag ie:
addhist 1 hsd/99-99-9999

Expected behavior
invalid date exception
Screenshots

Additional context
Add any other context about the problem here.

---

Reported by: @BearPerson1
Severity: High

_{[original: nusCS2113-AY1819S1/pe-1#172]}

[xShaivan]

Our team has implemented a standardized date/time check which resolves this issue and will be found in the v1.4 release. Thank you for the feedback!