Inaccurate error message for add order

[ki1r0]

##Description
the error message for invalid add order command is inaccurate

##Steps to reproduce
add order 1 -pn Croissant -q 2 -pn Apple Pie -q 2 -pn

##Expected
as the name of the last bakery is not specified, the error message should be warning that says bakery name not specified, or invalid format, or missing parameter etc

##Actual
error message:
Quantity must be a positive integer between 1 - 999

##Screenshots

[nus-se-script]

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