What is the error meaning?

Hi @kanagakumar, I managed to get it up and running with a few tweaks. Probably was corrupted by text formatting. Also was missing a check for undefined myText[i]. - Mark

if (app.documents.length > 0) {
    var myDocument = app.documents[0];
    //----------------------------Open Dialog box----------------------------//
    var myStylesNames = [];
    for (i = 0; i < myDocument.allParagraphStyles.length; i++) {
        myStylesNames.push(myDocument.allParagraphStyles[i].name);
    }
    var myDialog = app.dialogs.add({
        name: "Align to dots script",
        canCancel: true
    });
    with (myDialog.dialogColumns.add()) {
        staticTexts.add({
            staticLabel: "Choose the paragraph style applied to the cells you want to align on dot"
        });
    }

    with (myDialog.dialogColumns.add()) {
        var myDDSTyles = dropdowns.add({
            stringList: myStylesNames,
            selectedIndex: 0
        });
    }
    var myResult = myDialog.show();
    if (myResult == true) {
        var myParaStyle = myStylesNames[myDDSTyles.selectedIndex];
    }
    myDialog.destroy();
    //---------------------------- add a tab before (if doesn't exist) ----------------------------//
    app.findGrepPreferences = null;
    app.changeGrepPreferences = null;
    app.findGrepPreferences.properties = {
        findWhat: "^(\\d)",
        appliedParagraphStyle: myParaStyle,
    }
    app.changeGrepPreferences.changeTo = "\\t$1";
    app.activeDocument.changeGrep();
    app.findGrepPreferences = null;
    app.changeGrepPreferences = null;
    //---------------------------- create array ----------------------------//
    var myText = [];
    var allText = myDocument.stories.everyItem().tables.everyItem().cells.everyItem().paragraphs.everyItem().getElements();
    for (i = 0; i < allText.length; i++) {
        if (allText[i].appliedParagraphStyle.name == myParaStyle) {
            myText.push(allText);
        }
    }
    //---------------------------- Set tab alignment and apply to cells ----------------------------//
    var tabStopProperties = {
        alignment: TabStopAlignment.CHARACTER_ALIGN,
        alignmentCharacter: "."
    };
    for (var i = 0; i < myText.length; i++) {

        if (myText[i].parent == undefined)continue;
        var cellWidth = myText[i].parent.width;
        var cellLeftInset = myText[i].parent.leftInset;
        var cellRightInset = myText[i].parent.rightInset;
        var position = (cellWidth - cellRightInset - cellLeftInset - 1.058) / 2;
        myText[i].tabStops.everyItem().remove();
        myText[i].tabStops.add();
        myText[i].tabStops[0].properties = tabStopProperties;
        myText[i].tabStops[0].position = position;
    }
} else {
    alert("Please open a document");
}