How to catch user interface event trigger error - events

Question

How to catch error from ser interface event trigger.
For example, in the code below, f6 is updating the data in the ttnom temporary table. In the fill_tt procedure, if the table is empty, PROGRESS.lang.apperror('Temp-table is empty') is thrown.
Is it possible to return it from the F6 event to the main block of the program so that it is caught there by the catch block, and not by the catch inside the event.
BLOCK-LEVEL ON ERROR UNDO, THROW.
DEFINE VARIABLE inomtr AS i NO-UNDO.
DEFINE VARIABLE lexit AS L NO-UNDO.
DEFINE TEMP-TABLE ttnom NO-UNDO
FIELD uid AS int64
INDEX idx1 IS unique uid.
DEFINE FRAME fupd
SKIP(1)
inomtr FORMAT '>>>>>>>>>>>9' NO-LABEL
SKIP(1)
WITH VIEW-AS DIALOG-BOX SIDE-LABELS.
ON GO OF FRAME fupd
DO:
_t1:
DO ON ERROR UNDO, RETURN NO-APPLY:
ASSIGN inomtr.
IF CAN-FIND (FIRST ttnom NO-LOCK WHERE ttnom.uid = inomtr) THEN
LEAVE _t1.
MESSAGE 'inomtr not found' VIEW-AS ALERT-BOX.
RETURN NO-APPLY.
END.
END.
ON F3 OF inomtr IN FRAME fupd
DO:
RUN choose_nom(OUTPUT inomtr).
END.
ON F6 of FRAME fupd ANYWHERE
DO:
DO ON ERROR UNDO, THROW :
RUN fill_tt.
CATCH ERROR AS PROGRESS.lang.error:
message error:GetMessage(1) + return-value VIEW-AS ALERT-BOX.
lexit = YES.
STOP.
END CATCH.
END.
RETURN NO-APPLY.
END.
_tr:
DO ON ERROR UNDO, THROW
ON STOP UNDO, LEAVE
ON ENDKEY UNDO, LEAVE:
RUN fill_tt.
DO WHILE TRUE ON ERROR UNDO, throw
ON STOP UNDO , RETRY
ON ENDKEY UNDO , RETRY :
IF RETRY OR lexit = yes THEN
DO:
IF lexit = NO THEN
MESSAGE 'Exit?' VIEW-AS ALERT-BOX BUTTONS YES-NO UPDATE lexit.
IF lexit = YES THEN
LEAVE _tr.
END.
DISPLAY WITH FRAME fupd.
ENABLE inomtr WITH FRAME fupd.
WAIT-FOR GO OF FRAME fupd.
RUN do_nomtr(inomtr).
END.
CATCH ERROR AS PROGRESS.lang.error:
message ERROR:GetMessage(1) + RETURN-VALUE VIEW-AS ALERT-BOX.
END CATCH.
END.
PROCEDURE do_nomtr:
DEFINE INPUT PARAM inomtr AS i NO-UNDO.
MESSAGE inomtr VIEW-AS ALERT-BOX.
END PROCEDURE.
PROCEDURE fill_tt:
DO ON ERROR UNDO, THROW:
DISPLAY 'Loading temp-table' WITH FRAME ftt VIEW-AS DIALOG-BOX.
EMPTY TEMP-TABLE ttnom.
FOR EACH link NO-LOCK WHERE link.type = 3 AND link.class-code = '1B' AND
link.file-name = 'r-goods' AND link.arch = no ON ERROR UNDO, THROW:
IF CAN-FIND(FIRST ttnom WHERE ttnom.uid = link.link-num) THEN
NEXT.
CREATE ttnom.
ASSIGN ttnom.uid = link.link-num.
END.
HIDE FRAME ftt NO-PAUSE.
IF NOT TEMP-TABLE ttnom:HAS-RECORDS THEN
UNDO, THROW NEW PROGRESS.lang.apperror('Temp-table is empty').
END.
END PROCEDURE.

Answer 1

The main-block cannot catch an error from a trigger. You should have a catch block in every trigger-block.
If you want to go beyond the wait-for (in the main-block) you need to apply the GO event.