message: Check evt type before reading pointer coordinates
diff: @@ -33,14 +33,13 @@ export function Pointer(size: ChunkSize): Pointer {
  }
  function read(evt: any, axis: Axis): Vector1D {
  - const { isMouse } = state
  + state.isMouse = !evt.touches
  const c = coords[axis]
  - const value = isMouse ? evt[c] : evt.touches[0][c]
  + const value = state.isMouse ? evt[c] : evt.touches[0][c]
  return pointValue.setNumber(value)
  }
  function down(evt: Event): number {
  - state.isMouse = !!evt.type.match(/mouse/)
  const point = read(evt, 'x')
  startDrag.set(point)
  lastDrag.set(point)
  