graphics/grOGL1.c Dereference of null pointer

Looks like the code below requires mw!=NULL to do anything useful.
So when mw==NULL we don't continue processing X11 Event.

SonarCloud
graphics/grOGL1.c:563 Dereference of null pointer
https://sonarcloud.io/project/issues?open=AZJB16z6NGfDNup0Riss&id=dlmiles_magic

graphics/grOGL1.c

@@ -557,6 +557,8 @@ pipehandler()
 
 	entry = HashLookOnly(&grOGLWindowTable, ExposeEvent->window);
 	mw = (entry) ? (MagWindow *)HashGetValue(entry) : 0;
+	if(!mw)
+	    break;
 
 	screenRect.r_xbot = ExposeEvent->x;
 	screenRect.r_xtop = ExposeEvent->x + ExposeEvent->width;