fix(data): show error when --data mixes data types

[reubenmiller]

Invalid shorthand json provided by the user on --data no longer panics. Instead an more helpful error message is given to the user.

Previously the following would cause a panic because the one property is being used to assing both a number and an object.

Example

Below shows the new behaviour (e.g. error message instead of a panci):

c8y devices create -n --data one=1 --data one.two=null --dry

2024-05-18T23:17:04.910+0200    ERROR   commandError: json error: data parameter does not contain valid json or shorthand json. Invalid shorthand JSON: mixed types detected. trying to assign an object to a float64. path=one