fgl_report_getErrorString
Returns a human-readable error string.
Syntax
fgl_report_getErrorString() 
  RETURNING message STRING
      - message - An error description if an error occurred, an empty string otherwise.
 
Usage
This function returns the most recent error string. The function should be called after
        calling OUTPUT TO REPORT and FINISH REPORT. Calling the
        function at any other point in time may return random results. In case of an error, the
        function returns a human readable description of the error.