Topo2: Bug fixes
1: port lables not showing on mouseover
2: D3 Errors when there are no topology errors and a user pans/zooms

Change-Id: Ic65ba393d23b60673c3a731d1986ee15bbe1bd88
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2NodePosition.js b/web/gui/src/main/webapp/app/view/topo2/topo2NodePosition.js
index e29c45b..f30401f 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2NodePosition.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2NodePosition.js
@@ -128,6 +128,12 @@
     }
 
     function coordFromXY(loc) {
+
+        // Something this is wrong in the config
+        if (!t2sls.getWidth() || !t2sls.getHeight()) {
+            return [0, 0];
+        }
+
         var scale = 1000 / t2sls.getWidth(),
             yOffset = (1000 - (t2sls.getHeight() * scale)) / 2;