Compatibility with ppp asked?

[faanskit]

Prerequisites:

Running a Node.js server on a Raspberry Pi with a CAT-M1 modem attached, using pppd to connect to the internet via ppp0.
Pppd is using the modem via /dev/ttyUSB3 and the node.js query the modem via nodegsm.

Modules:

• express
• express-session
• http
• ws
• patch
• body-parser
• nodegsm

All worked fine before I added a simple 'onoff' driven button, with simple code.
The code does what it is expected to do. At button press, info is sent on the websocket.

// Push Button
const pushButton = new Gpio(4, 'in', 'rising', {debounceTimeout: 10}); 

// Close on kill
 function unexportOnClose() {
     pushButton.unexport(); // Unexport Button GPIO to free resources
 };
 process.on('SIGINT', unexportOnClose);

// Watch for buttonpush
 pushButton.watch(function (err, state) {
     if (err) {
       console.error('There was an error with the button', err);
     return;
     }
     if(state === 1){
         wss.clients.forEach(client => {
             if (client.readyState === WebSocket.OPEN) {
                 sendButton(client, "RISING")
             }
         });
     }
 });

Issue:
After I added this code, the pppd will not start properly. It will connect, but immediately disconnect from a SIGTERM signal.
If I comment out the onoff code, it all works fine again.

Looking for guidance and advice on how I can use this module with pppd, and if anyone has succesfully done that.

I have a hunch that it might be related to low level interrupt handing of this module, but that is pure speculation.

Any advice appreciated.

/Marcus