Exception given that hinders user input

[nus-pe-bot]

Issue description
It is stated that my productive hours in a day is 12 hours.
I added a class that last for 1 hour that day.
Exception thrown when adding cca that last for 1 hour the same day

Steps to reproduce the issue

1. add class /n Science class /s 2020-11-16 1000 /e 2020-11-16 1001
2. add cca /n tennis /s 2020-11-15 1200 /e 2020-11-15 1300

What’s the expected result?
Successful addition of the cca

What’s the actual result?

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_{[original: nus-cs2113-AY2021S1/pe-interim#3060]}

[durianpancakes]

Team's Response

No response provided.

Duplicate status (if any):

Duplicate of #3067