TypeError: Cannot read properties of undefined (reading 'fileName')

[chiaminghong]

I am following the hashlip youtube video - Code generate art Update Part 1.
https://www.youtube.com/watch?v=Ksb3JIomuqM&list=PLvfQp12V0hS3AVImYdMNfkdvRtZEe7xqY&index=5

Dont really understand why I Keep getting the error below when fileName existed.
Sometimes, the result returns more than 1 but it got stuck after another try.

PS D:\PROJECTS\test> node .\index.js 3
[]
created 91390203887582
red big_sr.png
D:\PROJECTS\test\index.js:54
${_layer.location}${_layer.selectedElement.fileName}
^
TypeError: Cannot read properties of undefined (reading 'fileName')
at D:\PROJECTS\test\index.js:54:57
at new Promise ()
at loadLayerImg (D:\PROJECTS\test\index.js:51:12)
at D:\PROJECTS\test\index.js:117:37
at Array.forEach ()
at startCreating (D:\PROJECTS\test\index.js:116:21)
at Object. (D:\PROJECTS\test\index.js:140:1)
at Module._compile (node:internal/modules/cjs/loader:1097:14)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1149:10)
at Module.load (node:internal/modules/cjs/loader:975:32)

Here are my codes:

const startCreating = async () => {
    writeMetaData("");
    let editionCount = 1;
 
    while(editionCount <= editionSize) {
        let newDna = createDna(layers.length * 2 - 1);
        console.log(dnaList);
        if (isDnaUnique(dnaList, newDna)) {
            console.log(`created ${newDna}`);
            let results = constructLayerToDna(newDna, layers);
            let loadedElements = []; //promise array
           
            results.forEach ((layer) => {
                loadedElements.push(loadLayerImg(layer)); 
            })

         await Promise.all(loadedElements).then((elementArray) => {
                elementArray.forEach((element) => {
                    drawElement(element);
                });

                signImage(`${editionCount}`);
                saveImage(editionCount);
                addMetadata(newDna, editionCount);
                console.log(`Created edition: ${editionCount} with DNA: ${newDna}`);
            });

            dnaList.push(newDna);
            editionCount++;
        } else {
            console.log("DNA Exists!!");
        }
    }
    writeMetaData(JSON.stringify(metadataList));
};

is it something wrong with the while loop and layer images??

images of my layers

would appreciate some explanation if possible.