Throw exception if undefined passed to putValue
Throw exception if undefined passed to putValue

- Makes it easier to figure out what happened

amorygalili/pynetworktables2js,amorygalili/pynetworktables2js,robotpy/pynetworktables2js,amorygalili/pynetworktables2js,robotpy/pynetworktables2js,amorygalili/pynetworktables2js,robotpy/pynetworktables2js,robotpy/pynetworktables2js