TypeError when interacting with OrbitControls with touch and mouse

• three version: v174
• Chrome, Windows

Problem description:

• Open https://threejs.org/examples/misc_controls_orbit.html with a PC that has a touch screen and a mouse
• Click and hold on the canvas with a mouse
• Touch the canvas with your finger (still keeping the mouse button down)

This is triggered:

OrbitControls.js:932 Uncaught TypeError: Cannot read properties of undefined (reading 'x')
    at OrbitControls._handleTouchStartDolly (OrbitControls.js:932:37)
    at OrbitControls._handleTouchStartDollyPan (OrbitControls.js:943:31)
    at OrbitControls.onTouchStart (OrbitControls.js:1428:11)
    at OrbitControls.onPointerDown (OrbitControls.js:1172:8)

Suggested solution:

OrbitControls seems to maintain pointers array using onPointerDown and other pointer events, but maintains pointerPositions using only touch events. Not all pointer events are touch events, so those two arrays are not in sync, and that is why getSecondPointerPosition returns undefined.

Reproduce the issue in the linked misc_controls_orbit.html example using a touchscreen PC and mouse. Then inspect OrbitControls.js around onPointerDown, onTouchStart, _handleTouchStartDolly and getSecondPointerPosition, focusing on how pointers and pointerPositions are updated. Done means the mixed mouse-and-touch interaction no longer raises the reported TypeError.