gettextprop: check result of XGetTextProperty (undefined behaviour for XFree)

dwm.c

@@ -910,8 +910,7 @@ gettextprop(Window w, Atom atom, char *text, unsigned int size)
 	if (!text || size == 0)
 		return 0;
 	text[0] = '\0';
-	XGetTextProperty(dpy, w, &name, atom);
-	if (!name.nitems)
+	if (!XGetTextProperty(dpy, w, &name, atom) || !name.nitems)
 		return 0;
 	if (name.encoding == XA_STRING)
 		strncpy(text, (char *)name.value, size - 1);