500 error for Botbox POST

botboxes_500_errors_for_post.json

{
  "error": "The server encountered an error! We have no idea what went wrong.",
  "debug": {
    "message": "Nullable object must have a value.",
    "stackTrace": "at System.Nullable`1<long>.get_Value () <0x00056>\nat (wrapper dynamic-method) object.lambda_method (System.Runtime.CompilerServices.Closure,Botlink.Core.Models.Identity.BotBox) <0x00055>\nat FluentValidation.Internal.Extensions/<>c__DisplayClass1`2<Botlink.Core.Models.Identity.BotBox, long>.<CoerceToNonGeneric>b__0 (object) <0x00048>\nat FluentValidation.Validators.PropertyValidatorContext.get_PropertyValue () <0x0003e>\nat FluentValidation.Validators.PropertyValidator.Validate (FluentValidation.Validators.PropertyValidatorContext) <0x00074>\nat FluentValidation.Internal.PropertyRule.InvokePropertyValidator (FluentValidation.ValidationContext,FluentValidation.Validators.IPropertyValidator,string) <0x00068>\nat FluentValidation.Internal.PropertyRule/<Validate>d__10.MoveNext () <0x003f9>\nat System.Linq.Enumerable/<CreateSelectManyIterator>c__Iterator12`2<FluentValidation.IValidationRule, FluentValidation.Results.ValidationFailure>.MoveNext () <0x0034f>\nat System.Collections.Generic.List`1<FluentValidation.Results.ValidationFailure>.AddEnumerable (System.Collections.Generic.IEnumerable`1<FluentValidation.Results.ValidationFailure>) <0x0009f>\nat System.Collections.Generic.List`1<FluentValidation.Results.ValidationFailure>..ctor (System.Collections.Generic.IEnumerable`1<FluentValidation.Results.ValidationFailure>) <0x000ee>\nat System.Linq.Enumerable.ToList<FluentValidation.Results.ValidationFailure> (System.Collections.Generic.IEnumerable`1<FluentValidation.Results.ValidationFailure>) <0x00056>\nat FluentValidation.AbstractValidator`1<Botlink.Core.Models.Identity.BotBox>.Validate (FluentValidation.ValidationContext`1<Botlink.Core.Models.Identity.BotBox>) <0x001b9>\nat FluentValidation.AbstractValidator`1<Botlink.Core.Models.Identity.BotBox>.Validate (Botlink.Core.Models.Identity.BotBox) <0x000ca>\nat FluentValidation.AbstractValidator`1<Botlink.Core.Models.Identity.BotBox>.FluentValidation.IValidator.Validate (object) <0x00091>\nat Nancy.Validation.FluentValidation.FluentValidationValidator.Validate (object,Nancy.NancyContext) <0x00027>\nat Nancy.Validation.ModuleExtensions.Validate<Botlink.Core.Models.Identity.BotBox> (Nancy.INancyModule,Botlink.Core.Models.Identity.BotBox) <0x000a2>\nat Nancy.ModelBinding.ModuleExtensions.BindAndValidate<Botlink.Core.Models.Identity.BotBox> (Nancy.INancyModule,string[]) <0x00075>\nat Botlink.Api.Modules.Helpers.CrudModule`2<Botlink.Core.Models.Identity.BotBox, Botlink.Core.Data.IBotBoxDb>.<CrudModule>m__1 (object) <0x0006d>\nat (wrapper dynamic-method) object.CallSite.Target (System.Runtime.CompilerServices.Closure,System.Runtime.CompilerServices.CallSite,System.Func`2<object, object>,object) <0x000a0>\nat Nancy.Routing.Route/<>c__DisplayClass4.<Wrap>b__3 (object,System.Threading.CancellationToken) <0x0014e>\n",
    "baseExceptionMessage": "Nullable object must have a value."
  }
}