Displaying all appliances when no location is given on list command

[nus-pe-bot]

It might good to throw an error message when no location is input instead of displaying all appliances (this is just my opinion :D). Regardless, this detail can be included in the UserGuide so user can better understand the program.

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_{[original: nus-cs2113-AY2021S1/pe-interim#575]}

[zongxian-ctrl]

Team's Response

Program working as intended, bug was reported as an opinion so shouldnt consider as a bug.

Duplicate status (if any):

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