Topo2: Handle regions without a map/sprite

Change-Id: Ifa944499992843c1506462caae0e1646b204996b
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2Link.js b/web/gui/src/main/webapp/app/view/topo2/topo2Link.js
index e94ed6c..fbdeab3 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2Link.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2Link.js
@@ -299,6 +299,9 @@
                 }
             },
             setScale: function () {
+
+                if (!this.el) return;
+
                 var width = linkScale(widthRatio) / t2zs.scale();
                 this.el.style('stroke-width', width + 'px');