Indesign Javascript – adding a hyperlink text source

Hi

I am a bit stuck and hoping someone can help me figure out where I am going wrong.

I have added my script below and the part that I keep getting an error on is line line 62 but I believe the actualy error is in line 60 where I am defining the variable mySelection for adding in the hyperlink.

The error I get says "Error Number: 45. Error String: Object is invalid"

I have tested the index variables for the start and the end of the selection and they are correct. I have another script for applying a hyperlink that works in a very similar but slightly different way – it applies the hyperlink to text I have highlighted – and the logic is the same here but I can't see where I am going wrong?

const doc = app.activeDocument;
createTOC();
function createTOC() {

    //********************************************** TEST FOR STYLES **********************************************
    testStyles()
    //********************************************** SETUP THE DOCUMENT **********************************************
    //Create a text frame on page 3 for the TOC to go into
    var textFrame = doc.pages[3].textFrames.add();
    textFrame.properties = {
        geometricBounds: [-171.601, 244.375, 33.155, 361.25],
        strokeWidth: 0,
        fillColor: "None",
        contents: "",
        itemLayer: "Text",
    };
    //Apply the paragraph style to the TOC frame
    textFrame.texts[0].appliedParagraphStyle = doc.paragraphStyleGroups.itemByName("Inside Front Pages").paragraphStyles.itemByName("TOC_Contents");

    //****************************************** Capture the Recipe Name and Cirlcle Letter Pairs *********************************************
    //this functions returns a multidimensional array – each entry has the recipe name followed by the circle letters 
    var recipeData = getRecipeData();

    //********************************* CREATE THE TOC *************************************
    var arrayLength = recipeData.length;

    for (var j = 0; j < 5; j++) {
        var tocRecipeName = recipeData[j][0];
        var tocCircleLetters = recipeData[j][1];

        //**************************** ADD IN CROSS REFERENCE **********************************
        //put in the destination
        var h = doc.hyperlinkTextDestinations.itemByName(tocRecipeName);
        //Where is the location for the cross reference to be inserted
        var t = doc.pages[3].textFrames[1].insertionPoints[-1];
        //What format should the cross reference use
        var xRefForm = doc.crossReferenceFormats.item("Page Number");
        //Add the values for the destination and type of cross refernce format
        var s = doc.crossReferenceSources.add(t, xRefForm);
        //create the cross reference
        var xref = doc.hyperlinks.add(s, h);

        //********************************* INSERT THE RECIPE NAME *************************************
        //select the text frame on the contents page
        var myTextFrame = doc.pages[3].textFrames[1];
        //Define the text to be inserted
        var myNewText = "\t" + tocRecipeName;
        //Put the recipe name into the text frame
        myTextFrame.parentStory.insertionPoints.item(-1).contents = myNewText;

        //********************************* ADD HYPERLINK TO THE RECIPE NAME *************************************
        //get the idex position for the start and end of the Recipe Name
        var indexEnd = myTextFrame.characters.length;
        var recipeLength = tocRecipeName.length;
        var indexStart = indexEnd - recipeLength;

        //**************************** ADD IN THE HYPERLINK **********************************

        //select the text by their index numbers previously defined.
        var mySelection = myTextFrame.characters.itemByRange(indexStart, indexEnd);
        //apply the character style to it.
        mySelection.appliedCharacterStyle = "Hyperlink";

        //The below defines the source of the hyperlink to be the highlighted text "mySelection"
        var source = app.documents[0].hyperlinkTextSources.add(mySelection);
        //Destination"s" plural is used because we are selecting (via its name) a single hyperlink destination from the ARRAY of possible destinations. 
        var dest = app.documents[0].hyperlinkTextDestinations.itemByName(tocRecipeName);

        //this applies the hyperlink referencing the source and the destination 
        app.documents[0].hyperlinks.add(source, dest, {
            name: "TOC_" + tocRecipeName
        });


    }
}