Make sure we always have a valid container element before calculating the dimensions of the various charts

static/js/graphing.js

@@ -139,6 +139,7 @@ ImageHistoryTree.prototype.setupOverscroll_ = function() {
 ImageHistoryTree.prototype.updateDimensions_ = function() {
   var container = this.container_;
   var dimensions = this.calculateDimensions_(container);
+  if (!dimensions) { return; }
 
   var m = dimensions.m;
   var w = dimensions.w;
@@ -909,6 +910,10 @@ function FileTreeBase() {
  */
 FileTreeBase.prototype.calculateDimensions_ = function(container) {
   var containerElm = document.getElementById(container);
+  if (!containerElm) {
+    return null;
+  }
+
   var cw = containerElm ? containerElm.clientWidth : 1200;
   var barHeight = 20;
   var ch = (this.getNodesHeight() * barHeight) + 40;
@@ -940,6 +945,7 @@ FileTreeBase.prototype.updateDimensions_ = function() {
 
   var container = this.container_;
   var dimensions = this.calculateDimensions_(container);
+  if (!dimensions) { return; }
 
   var w = dimensions.w;
   var h = dimensions.h;
@@ -989,6 +995,7 @@ FileTreeBase.prototype.draw = function(container) {
   this.container_ = container;  
   
   var dimensions = this.calculateDimensions_(container);
+  if (!dimensions) { return; }
   
   var w = dimensions.w;
   var h = dimensions.h;
@@ -1107,6 +1114,8 @@ FileTreeBase.prototype.getVisibleCount_ = function(node) {
  */
 FileTreeBase.prototype.getContainerHeight_ = function() {
   var dimensions = this.calculateDimensions_(this.container_);
+  if (!dimensions) { return; }
+
   var barHeight = this.barHeight_;
   var height = (this.getVisibleCount_(this.root_) * (barHeight + 2)); 
   return height + dimensions.m[0] + dimensions.m[2];