test fix

src/client/canvas.ts

@@ -170,6 +170,7 @@ export class ViewCanvas {
     });
 
     this._wrapper.addEventListener('touchstart', (ev: TouchEvent) => {
+      ev.preventDefault();
       const touch = ev.touches[0] || ev.changedTouches[0];
       this._mousex = touch.pageX;
       this._mousey = touch.pageY;