Ensure TimeAxis w/o orientation fails cleanly

Fix minor bug where if TimeAxis is instantiated w/o an orientation, it fails
in a hard-to-decipher way because the orientation.toLowerCase() breaks on
input before the AbstractAxis class has a chance to throw a proper error.
This bugs me for some reason where the error is throw after the variables are set to the instance variables.  What happens if there is an error after the instance variables are set?