Hey @Steve-Mcl,
I still couldn't call the extraFunctionality function this evening in my real node code, but it worked fine in the simplified version like you already pointed out. Seemed after all that my node was calling the code (to add the extraFunctionality function to the prototype) too late in the process.
But thanks to your confirmation that my code should work, I manage to troubleshoot and solve it by simply moving my code snippet to another location...
I really appreciate that you took the time to test my code snippet in VsCode!!!!!!!!
Bart