adding ingredients without expiry date does not remove it

[LeeMingDe]

Steps to reproduce:

1. type in command box add ingredient milk /qty 1l
2. press enter

[nus-se-bot]

Team's Response

As per section 4.8 of our User Guide, ChopChop only displays the earliest expiry date out of all the ingredient sets that exist.

Items for the Tester to Verify

:question: Issue response

Team chose [response.Rejected]

• [ ] I disagree

Reason for disagreement: [replace this with your explanation]

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:question: Issue type

Team chose [type.FunctionalityBug] Originally [type.FeatureFlaw]

• [ ] I disagree

Reason for disagreement: [replace this with your explanation]

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:question: Issue severity

Team chose [severity.Medium] Originally [severity.Low]

• [ ] I disagree

Reason for disagreement: [replace this with your explanation]

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