conflick of functions ListGridField.setGroupTitleRenderer and Timeline.setDateHeaderCustomizer in Timeline

[Hirn]

Hello dear developers.
I have encountered a problem where using the setGroupTitleRenderer and setDateHeaderCustomizer functions in Timeline simultaneously leads to warnings and ignoring the setDateHeaderCustomizer function.

If I use these functions separately, everything works correctly.

Here's my code....

        ListGridField pageTitleField = new ListGridField("title", "title");
        pageTitleField.setWidth(200);

        ListGridField pageGroupField = new ListGridField(GROUP_ID);
        pageGroupField.setHidden(true);
        pageGroupField.setCanGroupBy(true);
        pageGroupField.setGroupTitleRenderer(new GroupTitleRenderer() {
            @Override
            public String getGroupTitle(Object groupValue, GroupNode groupNode, ListGridField field, String fieldName, ListGrid grid) {
                Record group = projectsTree.find("@id", groupValue);
                return group.getAttribute("title");
            }
        });

        HeaderLevel dayLevel = new HeaderLevel(TimeUnit.DAY);
        dayLevel.setHeaderWidth(50);
        HeaderLevel[] headerLevels = new HeaderLevel[]{
                new HeaderLevel(TimeUnit.WEEK),
                dayLevel
        };
        tasksLine = new Timeline();
        tasksLine.setHeight("100%");
        tasksLine.setHeaderLevels(headerLevels);
        tasksLine.setShowComplexFields(true);
        tasksLine.setShowIndicators(true);
        tasksLine.setShowIndicatorsInFront(true);
        tasksLine.setShowQuickEventDialog(false);
        tasksLine.setStartDate(currentDate);
        tasksLine.setCanRemoveEvents(false);
        tasksLine.setShowEventDescriptions(false);
        tasksLine.setCanEditLane(false);
        tasksLine.setLaneEventPadding(2);
        tasksLine.setLaneFields(pageTitleField, pageGroupField);
        tasksLine.setCanGroupLanes(true);
        tasksLine.setLaneGroupByField(GROUP_ID);
        tasksLine.setNameField("title");
        tasksLine.setHideUnusedLanes(false);
        tasksLine.setResolution(headerLevels, TimeUnit.MONTH, 1, null);
        tasksLine.setLanes(tasksLanes);

        tasksLine.setDateHeaderCustomizer(new DateHeaderCustomizer() {
            public String getHeaderTitle(Date date, int dayOfWeek, String defaultValue, CalendarView calendarView) {
                return DateTimeFormat.getFormat("d.M").format(date);
            }
        });

the following warnings appear

*11:26:22.654:TMR3[E0]:WARN:Log:Uncaught exception escaped: java.lang.AssertionError
undefined
    at G5_g$(com.bug.TestBug-0.js@8:441)
    at a6d_g$(com.bug.TestBug-0.js@9:1969)
    at new g6d_g$(com.bug.TestBug-0.js@10:2003)
    at V6c_g$(com.bug.TestBug-0.js@10:1835)
    at uFh_g$(com.bug.TestBug-0.js@20:131286)
    at qvg_g$(com.bug.TestBug-0.js@10:95096)
    at Oc_g$(com.bug.TestBug-0.js@10:6188)
    at bh_g$(com.bug.TestBug-0.js@14:7469)
    at <anonymous>(com.bug.TestBug-0.js@30:126780)
    at Eeb_g$(com.bug.TestBug-0.js@28:22498)
    at Heb_g$(com.bug.TestBug-0.js@16:22554)
    at getDateHeaderTitle(com.bug.TestBug-0.js@14:22534)
    at isc_CalendarView_getFieldTitle(http://127.0.0.1:8888/sc/modules/ISC_Calendar.js@507:59)
    at isc_ListGrid_getHeaderButtonTitle(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@200:2795)
    at buttonTitleFunction(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@358:2666)
    at isc_StatefulCanvas_getTitleHTML(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@229:199)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@162:298)
    at isc_Button_getTitleHTML(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@168:524)
    at isc_Button_getInnerHTML(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@431:485)
    at isc_Canvas__getInnerHTML(http://127.0.0.1:8888/sc/modules/ISC_Core.js@68:2918)
    at isc_Canvas__insertHTML(http://127.0.0.1:8888/sc/modules/ISC_Core.js@229:2994)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@220:2940)
    at isc_StatefulCanvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@431:195)
    at isc_Layout_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@264:339)
    at isc_Layout_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@640:248)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@162:298)
    at isc_Toolbar_draw(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@493:630)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@93:298)
    at isc_c_Class_Super(http://127.0.0.1:8888/sc/modules/ISC_Core.js@170:290)
    at draw(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@6:2727)
    at isc_Layout_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@264:339)
    at isc_Layout_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@640:248)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_ListGrid__updateFieldWidths(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@183:1357)
    at isc_ListGrid_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@66:1327)
    at isc_Layout_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@640:248)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@162:298)
    at isc_ListGrid_draw(http://127.0.0.1:8888/sc/modules/ISC_Grids.js@621:1412)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@93:298)
    at isc_c_Class_Super(http://127.0.0.1:8888/sc/modules/ISC_Core.js@170:290)
    at isc_CalendarView_draw(http://127.0.0.1:8888/sc/modules/ISC_Calendar.js@372:224)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@162:298)
    at isc_TimelineView_draw(http://127.0.0.1:8888/sc/modules/ISC_Calendar.js@72:397)
    at isc_Layout_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@264:339)
    at isc_Layout_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@640:248)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_Layout_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@205:337)
    at isc_Layout_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@640:248)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_Canvas_drawChildren(http://127.0.0.1:8888/sc/modules/ISC_Core.js@241:2986)
    at isc_Canvas_draw(http://127.0.0.1:8888/sc/modules/ISC_Core.js@253:2940)
    at isc_c_Class_invokeSuper(http://127.0.0.1:8888/sc/modules/ISC_Core.js@162:298)
    at isc_Calendar_draw(http://127.0.0.1:8888/sc/modules/ISC_Calendar.js@250:564)
    at isc_Layout_layoutChildren(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@264:339)
    at isc_Layout_reflowNow(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@568:371)
    at isc_c_Layout_clearReflowQueue(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@447:232)
    at anonymous(http://127.0.0.1:8888/sc/modules/ISC_Foundation.js@82:232)
    at isc_c_EventHandler_runTeas(http://127.0.0.1:8888/sc/modules/ISC_Core.js@106:2501)
    at isc_c_EventHandler__clearThread(http://127.0.0.1:8888/sc/modules/ISC_Core.js@136:2498)
    at isc_c_Timer__fireTimeout(http://127.0.0.1:8888/sc/modules/ISC_Core.js@210:2073)

Is this a Timeline component error? Or did I do something wrong?

PS.
My SmartGWT version is SNAPSHOT_v12.1d_2019-12-11

[Isomorphic]

There's an order-of-operations issue here, which we're looking into.

In the meantime, you can work around it - remove your call to tasksLine.setLaneGroupByField(GROUP_ID) and, instead, *wait until the timeline has been drawn* and then call tasksLine.groupLanesBy(GROUP_ID).