This is called to report an error in the user's program.
See PLT McMicMac: Parser Manual for the definition of the zodiac:zodiac struct.
The default behavior is to higlight the range from the start-location to end-location in the text named in the file field of start-location, if the file field is a text% instance.
If the file field is not an instance of text%, it will pop up a modal dialog with the error message and the source location.