Error when entering <=0 index when deleting #3
Description
When executing command "deletePerson 0", the error message is, "Index is not a non-zero unsigned integer."
It may not be a very user friendly error, as I think the error is coming from parsing the number into a Index type. Thus, I think a better error message may be like "Sorry, you have input an invalid number! Please try again".
Similar behaviour for deleteLocation.
