Accessing second input source in WebXR

I have existing code using Three.js and my own to move around inside an active WebXR environment. The code started crashing late last fall and I'm trying to figure out why. When only one controller is connected to the headset there is no problem. The same is true when deliberately using the first input source reported by Three.js. After manually switching to the second input source the experience crashes immediately upon entering VR. The error codes are not always the same but all have to do with trying to read properties of undefined variables. Since my code works fine for the first input source, there appears to be a firmware bug with respect to the second. Anyone else notice this? Is this a known bug?

FYI source code: https://github.com/paulmasson/paulmasson.github.io/blob/master/webxr-worlds/js/VRController.js