Javascript error 'deleteCell'

My Web app sometimes generates error messages like this one:

Could not execute returned javascript: Failed to execute ‘deleteCell’ on ‘HTMLTableRowElement’: The value provided (14) is outside the range [0, 1).
Source: Xojo.controls[‘LGmdKz10’].deleteAllRows();
Xojo.controls[‘LGmdKz10’].deleteAllRows();
Xojo.controls[‘LGmdKz10’].setColumnCount(14);
Xojo.controls[‘LGmdKz10’].setColumnStyle(0,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[0];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnStyle(1,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[1];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnStyle(2,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[2];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnStyle(3,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[3];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnStyle(4,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[4];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(5,‘Objektive Daten ø’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(5,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[5];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(6,‘Erzählsequenz ø’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(6,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[6];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(7,‘Entw.-Hyp. ø’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(7,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[7];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(8,‘Zus.fassg. ø’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(8,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[8];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(9,‘L/A/R’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(9,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[9];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(10,‘Ges.-Bew.’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(10,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[10];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(11,‘Kommentar’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(11,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[11];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(12,‘Klient.-Bew.’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(12,‘style_rightAlign’);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[12];
if(el) {
Xojo.DOM.removeClass(el,’_DefaultStyle’);
Xojo.DOM.addClass(el,‘style_rightAlign’);
}
Xojo.controls[‘LGmdKz10’].setColumnHeading(13,‘Abschluss am’);
Xojo.controls[‘LGmdKz10’].setColumnStyle(13,null);
var el = document.querySelector(’#LGmdKz10_headers tbody tr’).children[13];
if(el) {
Xojo.DOM.removeClass(el,‘style_rightAlign’);
Xojo.DOM.addClass(el,’_DefaultStyle’);
}
Xojo.controls[‘LGmdKz10’].setColumnWidths(‘50,160,80,140,140,140,140,140,140,80,80,300,140,135’);
Xojo.controls[‘LGmdKz10’].insertRow(0,[""]);
Xojo.controls[‘LGmdKz10’].setCellContents(0,0,“13373”);
Xojo.controls[‘LGmdKz10’].setCellContents(0,1,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,2,“fehlt seit 0 Tagen”);
Xojo.controls[‘LGmdKz10’].setCellContents(0,3,“Data, Firstname”);
Xojo.controls[‘LGmdKz10’].setCellContents(0,4,“Coach, Test”);
Xojo.controls[‘LGmdKz10’].setCellContents(0,5,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,6,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,7,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,8,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,9,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,10,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,11,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,12,"");
Xojo.controls[‘LGmdKz10’].setCellContents(0,13,“17.10.19”);
Xojo.controls[‘LGmdKz10’].insertRow(1,[""]);
Xojo.controls[‘LGmdKz10’].setCellContents(1,0,“12592”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,1,"");
Xojo.controls[‘LGmdKz10’].setCellContents(1,2,“ok”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,3,“Different, Lastname”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,4,“Some, Lastname”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,5,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,6,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,7,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,8,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,9,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,10,“10.00”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,11,“super!”);
Xojo.controls[‘LGmdKz10’].setCellContents(1,12,"");
Xojo.controls[‘LGmdKz10’].setCellContents(1,13,“05.06.19”);
Xojo.controls[‘RqZelrnG’].setMode(0);
Xojo.controls[‘GOSEzl77’].setVisible(false);
Xojo.controls[‘GOSEzl77’].refresh();
Xojo.controls[‘d7nTKYoo’].setValue(“2 Datensätze”);

Is my assumption that those javascript errors are basically always a bug in the Xojo WebFramework (and not in my code) correct?
I also reported this some time ago (feedback://showreport?report_id=56419), but as I can’t provide an example that reproduces the problem (it just doesn’t always happen) my case got closed without much ado. Can any of you guys make sense of the error message? Bad order of commands or something?

Thank you in advance, Max