diff --git a/blockly_compressed.js b/blockly_compressed.js
index 2fa7e761b1..1fd656d47f 100644
--- a/blockly_compressed.js
+++ b/blockly_compressed.js
@@ -1003,7 +1003,7 @@ a.clientY,this.startDragMetrics=this.getMetrics(),this.startScrollX=this.scrollX
 Blockly.WorkspaceSvg.prototype.startDrag=function(a,b,c){a=Blockly.mouseToSvg(a,this.options.svg);a.x/=this.scale;a.y/=this.scale;this.dragDeltaX_=b-a.x;this.dragDeltaY_=c-a.y};Blockly.WorkspaceSvg.prototype.moveDrag=function(a){a=Blockly.mouseToSvg(a,this.options.svg);a.x/=this.scale;a.y/=this.scale;return new goog.math.Coordinate(this.dragDeltaX_+a.x,this.dragDeltaY_+a.y)};
 Blockly.WorkspaceSvg.prototype.onMouseWheel_=function(a){Blockly.hideChaff(!0);Blockly.terminateDrag_();var b=0<a.deltaY?-1:1,c=Blockly.mouseToSvg(a,this.options.svg);this.zoom(c.x,c.y,b);a.preventDefault()};
 Blockly.WorkspaceSvg.prototype.showContextMenu_=function(a){if(!this.options.readOnly){var b=[];if(this.options.collapse){for(var c=!1,d=!1,e=this.getTopBlocks(!0),f=0;f<e.length;f++)for(var g=e[f];g;)g.isCollapsed()?c=!0:d=!0,g=g.getNextBlock();d={enabled:d};d.text=Blockly.Msg.COLLAPSE_ALL;d.callback=function(){for(var a=0,b=0;b<e.length;b++)for(var c=e[b];c;)setTimeout(c.setCollapsed.bind(c,!0),a),c=c.getNextBlock(),a+=10};b.push(d);c={enabled:c};c.text=Blockly.Msg.EXPAND_ALL;c.callback=function(){for(var a=
-0,b=0;b<e.length;b++)for(var c=e[b];c;)setTimeout(c.setCollapsed.bind(c,!1),a),c=c.getNextBlock(),a+=10};b.push(c)}Blockly.ContextMenu.show(a,b,this.RTL)}};Blockly.WorkspaceSvg.prototype.loadAudio_=function(a,b){if(window.Audio&&a.length){for(var c,d=new window.Audio,e=0;e<a.length;e++){var f=a[e],g=f.match(/\.(\w+)$/);if(g&&d.canPlayType("audio/"+g[1])){c=new window.Audio(f);break}}c&&c.play&&(this.SOUNDS_[b]=c)}};
+0,b=0;b<e.length;b++)for(var c=e[b];c;)setTimeout(c.setCollapsed.bind(c,!1),a),c=c.getNextBlock(),a+=10};b.push(c)}Blockly.ContextMenu.show(a,b,this.RTL)}};Blockly.WorkspaceSvg.prototype.loadAudio_=function(a,b){if(a.length){try{var c=new window.Audio}catch(d){return}for(var e,f=0;f<a.length;f++){var g=a[f],h=g.match(/\.(\w+)$/);if(h&&c.canPlayType("audio/"+h[1])){e=new window.Audio(g);break}}e&&e.play&&(this.SOUNDS_[b]=e)}};
 Blockly.WorkspaceSvg.prototype.preloadAudio_=function(){for(var a in this.SOUNDS_){var b=this.SOUNDS_[a];b.volume=.01;b.play();b.pause();if(goog.userAgent.IPAD||goog.userAgent.IPHONE)break}};
 Blockly.WorkspaceSvg.prototype.playAudio=function(a,b){var c=this.SOUNDS_[a];c?(c=goog.userAgent.DOCUMENT_MODE&&9===goog.userAgent.DOCUMENT_MODE||goog.userAgent.IPAD||goog.userAgent.ANDROID?c:c.cloneNode(),c.volume=void 0===b?1:b,c.play()):this.options.parentWorkspace&&this.options.parentWorkspace.playAudio(a,b)};
 Blockly.WorkspaceSvg.prototype.updateToolbox=function(a){if(a=Blockly.parseToolboxTree_(a)){if(!this.options.languageTree)throw"Existing toolbox is null.  Can't create new toolbox.";if(this.options.hasCategories){if(!this.toolbox_)throw"Existing toolbox has no categories.  Can't change mode.";this.options.languageTree=a;this.toolbox_.populate_(a)}else{if(!this.flyout_)throw"Existing toolbox has categories.  Can't change mode.";this.options.languageTree=a;this.flyout_.show(a.childNodes)}}else if(this.options.languageTree)throw"Can't nullify an existing toolbox.";
@@ -1104,10 +1104,10 @@ new Date,this.workspace.scale)};Blockly.BlockSvg.connectionUiStep_=function(a,b,
 Blockly.BlockSvg.prototype.updateColour=function(){if(!this.disabled){var a=Blockly.makeColour(this.getColour()),b=goog.color.hexToRgb(a),c=goog.color.lighten(b,.3),b=goog.color.darken(b,.2);this.svgPathLight_.setAttribute("stroke",goog.color.rgbArrayToHex(c));this.svgPathDark_.setAttribute("fill",goog.color.rgbArrayToHex(b));this.svgPath_.setAttribute("fill",a);a=this.getIcons();for(c=0;c<a.length;c++)a[c].updateColour();for(a=0;c=this.inputList[a];a++)for(var b=0,d;d=c.fieldRow[b];b++)d.setText(null)}};
 Blockly.BlockSvg.prototype.updateDisabled=function(){var a=Blockly.hasClass_(this.svgGroup_,"blocklyDisabled");this.disabled||this.getInheritedDisabled()?a||(Blockly.addClass_(this.svgGroup_,"blocklyDisabled"),this.svgPath_.setAttribute("fill","url(#blocklyDisabledPattern)")):a&&(Blockly.removeClass_(this.svgGroup_,"blocklyDisabled"),this.updateColour());for(var a=this.getChildren(),b=0,c;c=a[b];b++)c.updateDisabled()};
 Blockly.BlockSvg.prototype.getCommentText=function(){return this.comment?this.comment.getText().replace(/\s+$/,"").replace(/ +\n/g,"\n"):""};Blockly.BlockSvg.prototype.setCommentText=function(a){var b=!1;goog.isString(a)?(this.comment||(this.comment=new Blockly.Comment(this),b=!0),this.comment.setText(a)):this.comment&&(this.comment.dispose(),b=!0);b&&this.rendered&&(this.render(),this.bumpNeighbours_())};
-Blockly.BlockSvg.prototype.setWarningText=function(a,b){this.setWarningText.pid_||(this.setWarningText.pid_=Object.create(null));var c=b||"";if(c)this.setWarningText.pid_[c]&&(clearTimeout(this.setWarningText.pid_[c]),delete this.setWarningText.pid_[c]);else for(var d in this.setWarningText.pid_)clearTimeout(this.setWarningText.pid_[d]),delete this.setWarningText.pid_[d];if(2==Blockly.dragMode_){var e=this;this.setWarningText.pid_[c]=setTimeout(function(){delete e.setWarningText.pid_[c];e.setWarningText(a,
-c)},100)}else{this.isInFlyout&&(a=null);d=this.getSurroundParent();for(var f=null;d;)d.isCollapsed()&&(f=d),d=d.getSurroundParent();f&&f.setWarningText(a,"collapsed "+this.id+" "+c);d=!1;goog.isString(a)?(this.warning||(this.warning=new Blockly.Warning(this),d=!0),this.warning.setText(a,c)):this.warning&&!c?(this.warning.dispose(),d=!0):this.warning&&(d=this.warning.getText(),this.warning.setText("",c),(f=this.warning.getText())||this.warning.dispose(),d=d==f);d&&this.rendered&&(this.render(),this.bumpNeighbours_())}};
-Blockly.BlockSvg.prototype.setMutator=function(a){this.mutator&&this.mutator!==a&&this.mutator.dispose();a&&(a.block_=this,this.mutator=a,this.rendered&&a.createIcon())};Blockly.BlockSvg.prototype.setDisabled=function(a){this.disabled!=a&&(Blockly.BlockSvg.superClass_.setDisabled.call(this,a),this.rendered&&this.updateDisabled(),this.workspace.fireChangeEvent())};Blockly.BlockSvg.prototype.addSelect=function(){Blockly.addClass_(this.svgGroup_,"blocklySelected");this.svgGroup_.parentNode.appendChild(this.svgGroup_)};
-Blockly.BlockSvg.prototype.removeSelect=function(){Blockly.removeClass_(this.svgGroup_,"blocklySelected")};Blockly.BlockSvg.prototype.addDragging=function(){Blockly.addClass_(this.svgGroup_,"blocklyDragging")};Blockly.BlockSvg.prototype.removeDragging=function(){Blockly.removeClass_(this.svgGroup_,"blocklyDragging")};
+Blockly.BlockSvg.prototype.setWarningText=function(a,b){this.setWarningText.pid_||(this.setWarningText.pid_=Object.create(null));var c=b||"";if(c)this.setWarningText.pid_[c]&&(clearTimeout(this.setWarningText.pid_[c]),delete this.setWarningText.pid_[c]);else for(var d in this.setWarningText.pid_)clearTimeout(this.setWarningText.pid_[d]),delete this.setWarningText.pid_[d];if(2==Blockly.dragMode_){var e=this;this.setWarningText.pid_[c]=setTimeout(function(){e.workspace&&(delete e.setWarningText.pid_[c],
+e.setWarningText(a,c))},100)}else{this.isInFlyout&&(a=null);d=this.getSurroundParent();for(var f=null;d;)d.isCollapsed()&&(f=d),d=d.getSurroundParent();f&&f.setWarningText(a,"collapsed "+this.id+" "+c);d=!1;goog.isString(a)?(this.warning||(this.warning=new Blockly.Warning(this),d=!0),this.warning.setText(a,c)):this.warning&&!c?(this.warning.dispose(),d=!0):this.warning&&(d=this.warning.getText(),this.warning.setText("",c),(f=this.warning.getText())||this.warning.dispose(),d=d==f);d&&this.rendered&&
+(this.render(),this.bumpNeighbours_())}};Blockly.BlockSvg.prototype.setMutator=function(a){this.mutator&&this.mutator!==a&&this.mutator.dispose();a&&(a.block_=this,this.mutator=a,this.rendered&&a.createIcon())};Blockly.BlockSvg.prototype.setDisabled=function(a){this.disabled!=a&&(Blockly.BlockSvg.superClass_.setDisabled.call(this,a),this.rendered&&this.updateDisabled(),this.workspace.fireChangeEvent())};
+Blockly.BlockSvg.prototype.addSelect=function(){Blockly.addClass_(this.svgGroup_,"blocklySelected");this.svgGroup_.parentNode.appendChild(this.svgGroup_)};Blockly.BlockSvg.prototype.removeSelect=function(){Blockly.removeClass_(this.svgGroup_,"blocklySelected")};Blockly.BlockSvg.prototype.addDragging=function(){Blockly.addClass_(this.svgGroup_,"blocklyDragging")};Blockly.BlockSvg.prototype.removeDragging=function(){Blockly.removeClass_(this.svgGroup_,"blocklyDragging")};
 Blockly.BlockSvg.prototype.render=function(a){this.rendered=!0;var b=Blockly.BlockSvg.SEP_SPACE_X;this.RTL&&(b=-b);for(var c=this.getIcons(),d=0;d<c.length;d++)b=c[d].renderIcon(b);b+=this.RTL?Blockly.BlockSvg.SEP_SPACE_X:-Blockly.BlockSvg.SEP_SPACE_X;c=this.renderCompute_(b);this.renderDraw_(b,c);!1!==a&&((a=this.getParent())?a.render(!0):Blockly.fireUiEvent(window,"resize"));Blockly.Realtime.blockChanged(this)};
 Blockly.BlockSvg.prototype.renderFields_=function(a,b,c){this.RTL&&(b=-b);for(var d=0,e;e=a[d];d++){var f=e.getSvgRoot();f&&(this.RTL?(b-=e.renderSep+e.renderWidth,f.setAttribute("transform","translate("+b+","+c+")"),e.renderWidth&&(b-=Blockly.BlockSvg.SEP_SPACE_X)):(f.setAttribute("transform","translate("+(b+e.renderSep)+","+c+")"),e.renderWidth&&(b+=e.renderSep+e.renderWidth+Blockly.BlockSvg.SEP_SPACE_X)))}return this.RTL?-b:b};
 Blockly.BlockSvg.prototype.renderCompute_=function(a){var b=this.inputList,c=[];c.rightEdge=a+2*Blockly.BlockSvg.SEP_SPACE_X;if(this.previousConnection||this.nextConnection)c.rightEdge=Math.max(c.rightEdge,Blockly.BlockSvg.NOTCH_WIDTH+Blockly.BlockSvg.SEP_SPACE_X);for(var d=0,e=0,f=!1,g=!1,h=!1,k=void 0,l=this.getInputsInline()&&!this.isCollapsed(),q=0,m;m=b[q];q++)if(m.isVisible()){var p;l&&k&&k!=Blockly.NEXT_STATEMENT&&m.type!=Blockly.NEXT_STATEMENT?p=c[c.length-1]:(k=m.type,p=[],p.type=l&&m.type!=
diff --git a/core/block_svg.js b/core/block_svg.js
index 5dd8c387be..e7f5176b79 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -1252,8 +1252,10 @@ Blockly.BlockSvg.prototype.setWarningText = function(text, opt_id) {
     // Wait until the drag finishes.
     var thisBlock = this;
     this.setWarningText.pid_[id] = setTimeout(function() {
-      delete thisBlock.setWarningText.pid_[id];
-      thisBlock.setWarningText(text, id);
+      if (thisBlock.workspace) {  // Check block wasn't deleted.
+        delete thisBlock.setWarningText.pid_[id];
+        thisBlock.setWarningText(text, id);
+      }
     }, 100);
     return;
   }
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index bc9c9fdcd0..2030eec2db 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -702,12 +702,17 @@ Blockly.WorkspaceSvg.prototype.showContextMenu_ = function(e) {
  * @private
  */
 Blockly.WorkspaceSvg.prototype.loadAudio_ = function(filenames, name) {
-  if (!window['Audio'] || !filenames.length) {
+  if (!filenames.length) {
+    return;
+  }
+  try {
+    var audioTest = new window['Audio']();
+  } catch(e) {
     // No browser support for Audio.
+    // IE can throw an error even if the Audio object exists.
     return;
   }
   var sound;
-  var audioTest = new window['Audio']();
   for (var i = 0; i < filenames.length; i++) {
     var filename = filenames[i];
     var ext = filename.match(/\.(\w+)$/);