Fix blur edge for dense networks (#2124)

lib/network/modules/SelectionHandler.js

@@ -534,8 +534,9 @@ class SelectionHandler {
           this.hoverObj.edges[edgeId].hover = false;
           delete this.hoverObj.edges[edgeId];
         }
-        // if the blur remains the same and the object is undefined (mouse off), we blur the edge
-        else if (object === undefined) {
+        // if the blur remains the same and the object is undefined (mouse off) or another
+        // edge has been hovered, we blur the edge
+        else if (object === undefined || object instanceof Edge) {
           this.blurObject(this.hoverObj.edges[edgeId]);
           delete this.hoverObj.edges[edgeId];
           hoverChanged = true;