17/08/2021, no issues.
18/08/2021: For some reason overnight, there has been 0 changes in the code itself,
const pdfjsLib = window['pdfjs-dist/build/pdf']
pdfjsLib.GlobalWorkerOptions.workerSrc = '//mozilla.github.io/pdf.js/build/pdf.worker.js'
pdfjsLib stays undefined in the Electron app version of the application.
However, in the browser version, there is still no issue.
Hence, we can't work with PDFs anymore in the app. Who can explain how it suddenly doesn't work anymore after 1 year, and even better, who has a solution for this?