ERROR_TEXT
  Returns the text of the latest error message generated by DECTPU.  The
  value returned by ERROR_LINE is only meaningful inside an error handler.
  The value outside of an error handler is indeterminate.
  Syntax
     string := ERROR_LINE
  Parameters
     none
  Example
  The following code fragment is an error handler that uses ERROR_TEXT to
  report what error occurred:
     ON_ERROR
       MESSAGE (ERROR_TEXT);
       MESSAGE ("Error on line " + STR (ERROR_LINE);
       RETURN;
     ENDON_ERROR;
  Related Topics
     ERROR   ERROR_LINE   MESSAGE_TEXT