tclx_errorHandler message
The  tclx_errorHandler  command  doesn't  exist  as  built-in  part  of  TclX.
Instead, individual applications or  users  can  define   a  tclx_errorHandler
command (e.g. as a Tcl procedure) if they wish to handle uncaught errors.  The
procedure will be passed a single argument of the error message,  with  error-
Code and errorInfo having values reflecting the error that occurred.

The  tclx_errorHandler  command  is  called  when  an error that is not caught
returns to the top level command evaluation in the TclX shell or  wishx.   The
difference  between tclx_errorHandler and bgerror is that tclx_errorHandler is
called during the synchronous execution of a script while bgerror is called as
a  result  of  an uncaught error in an event handler.  In a non-event oriented
Tcl script tclx_errorHandler will be called on all errors that are not  caught
and  bgerror is not used.  In a wishx script or event oriented script executed
with the TclX shell, tclx_errorHandler will be called on uncaught errors  dur-
ing  the  execution of the main script that set up the event oriented program.
Once the event loop is entered, bgerror will be called on uncaught errors.

This procedure is not called in response to commands entered via  an  interac-
tive  command loop, only from the evaluation of scripts or Tcl commands passed
via the command line.  If the procedure returns  normally,  the  program  will
just  exit  without any error being issued by the shell.  Generally the proce-
dure should exit with a non-zero exit code once the error has been  processed.
It is not possible to continue executing the code in which the error occurred.
