Fixes issue with package errors before installation dialog is shown

Closes #1218

diff --git a/wcfsetup/install/files/acp/js/WCF.ACP.js b/wcfsetup/install/files/acp/js/WCF.ACP.js
index e1231cd582f308094d362a70f032ec2707c13268..783aa7060b853b7c91fc28996be2dad6847350ab 100644 (file)
--- a/wcfsetup/install/files/acp/js/WCF.ACP.js
+++ b/wcfsetup/install/files/acp/js/WCF.ACP.js
@@ -410,14 +410,16 @@ WCF.ACP.Package.Installation = Class.extend({
                        return;
                }
                
-               this._purgeTemplateContent($.proxy(function() {
-                       var $form = $('<div class="formSubmit" />').appendTo($('#packageInstallationInnerContent'));
-                       $('<button class="buttonPrimary">' + WCF.Language.get('wcf.acp.package.installation.rollback') + '</button>').appendTo($form).click($.proxy(this._rollback, this));
-                       
-                       $('#packageInstallationInnerContentContainer').show();
-                       
-                       this._dialog.wcfDialog('render');
-               }, this));
+               if (this._dialog !== null) {
+                       this._purgeTemplateContent($.proxy(function() {
+                               var $form = $('<div class="formSubmit" />').appendTo($('#packageInstallationInnerContent'));
+                               $('<button class="buttonPrimary">' + WCF.Language.get('wcf.acp.package.installation.rollback') + '</button>').appendTo($form).click($.proxy(this._rollback, this));
+                               
+                               $('#packageInstallationInnerContentContainer').show();
+                               
+                               this._dialog.wcfDialog('render');
+                       }, this));
+               }
        },
        
        /**