TSR demo company >> Server Error in candidate login while accepting offer letter

on Stage, in TSR demo company, Server Error in candidate login while accepting offer letter. PFA screen shot and error log.

Exception : Cannot insert the value NULL into column `EmailMessage`, table `TSRDemoCompany_12871.rct.EmailCommunication`; column does not allow nulls. INSERT

fails.The statement has been terminated.
App Error Log : ControllerAppTier.Save->RecruitControllerAppTier.Save->Candidate.SaveCandidateJobOfferDetails
Employee ID : 0
Action Name : SelectOfferStatusPopup
Model : System.Web.Mvc.HandleErrorInfo
Controller : OfferManagement
Web Error Log : at WORKTERRA.Recruit.RecruitControllerWebTier.Save(ObjectType I_objectType, Hashtable I_criteria, Object I_context)
at WORKTERRA.Recruit.Areas.Candidate.Models.OfferManagementModel.SaveOfferDetails(MyOfferSelectRejectModel objMyOfferSelectRejectModel)
at WORKTERRA.Recruit.Areas.Candidate.Controllers.OfferManagementController.SelectOfferStatusPopup(MyOfferSelectRejectModel objMyOfferSelectRejectModel)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2

parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass13.b_10()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor

actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)