System.NullReferenceException: Object reference not set to an instance of an object.
   at Vivace.Library.Cms.Factories.PublishedPageFactory.Convert(IAssignment assignment, DisplayContextType displayContextType, String parentId, String displayParentId) in D:\Accelerate Education\build\git\vivace\Vivace.Solution\Vivace.Library\Cms\Factories\PublishedPageFactory.cs:line 475
   at Vivace.Library.Cms.Factories.PublishedPageFactory.GetPublishedPageForLearningObject(Site site, String lessonId, String learningObjectId, String pageId, DisplayContextType displayContextType, String template, IEnumerable`1 formatives, UrlBundle bundle, StrandType strand, Nullable`1 workflow) in D:\Accelerate Education\build\git\vivace\Vivace.Solution\Vivace.Library\Cms\Factories\PublishedPageFactory.cs:line 155
   at Vivace.Ideal.Controllers.LessonController.CreatePublishedPageModel(String lessonId, String learningObjectId, String pageId, String template, List`1 formatives, String parentId, UrlBundle bundle, String strandAbbreviation, String enrollmentId, Nullable`1 workflowType, Nullable`1 packageGuid, Boolean speechstream, String speechstreamMode) in D:\Accelerate Education\build\git\vivace\Vivace.Solution\Vivace.Ideal\Controllers\LessonController.cs:line 1170
   at Vivace.Ideal.Controllers.LessonController.DisplayFullyQualifiedPublishedPage(String template, String bundle, String lessonId, String pageId, String enrollmentId, String strandAbbreviation, String parentAssignmentId, Nullable`1 workflowType, Nullable`1 packageGuid, Boolean speechStream, String speechStreamMode, Nullable`1 overrideConfig) in D:\Accelerate Education\build\git\vivace\Vivace.Solution\Vivace.Ideal\Controllers\LessonController.cs:line 560