Fix eventcatcher widget: check for event properties before accessing (#6048)

core/modules/widgets/eventcatcher.js

@@ -77,6 +77,7 @@ EventWidget.prototype.render = function(parent,nextSibling) {
 						variables["tv-selectednode-width"] = selectedNode.offsetWidth.toString();
 						variables["tv-selectednode-height"] = selectedNode.offsetHeight.toString();
 						
+						if(event.clientX && event.clientY) {
 							//Add variables for event X and Y position relative to selected node
 							selectedNodeRect = selectedNode.getBoundingClientRect();
 							variables["event-fromselected-posx"] = (event.clientX - selectedNodeRect.left).toString();
@@ -91,6 +92,7 @@ EventWidget.prototype.render = function(parent,nextSibling) {
 							variables["event-fromviewport-posx"] = event.clientX.toString();
 							variables["event-fromviewport-posy"] = event.clientY.toString();
 						}
+					}
 				} else {
 					return false;
 				}