Yes, the path for the github repository is three/examples/jsm/loaders/STLLoader.js
But the path from the npm package is three/example/js/loaders/STLLoader.js
Anyways, the last updates I have given is using the path from the github repository and it still does not get to work. It is like during the process to read the STL file it breaks. But it does not give any error back.
Will keep tracking this, if you have any news or there is anything I could try that you can think of, please tell me.
Thanks for all the help you already provided 