Erro ao tentar executar o Update-Database / PedidoId não pode ser nulo | ASP.NET Core parte 2: Melhorando sua webapp com validações e segurança.

Após criar a migração. E quando tento atualizar o banco (update-database) ocorre o seguinte erro:

...
IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
ClientConnectionId:d71595fd-156e-45ea-872b-37230ba63f9a
Error Number:515,State:2,Class:16
Cannot insert the value NULL into column 'PedidoId', table 'CasaDoCodigo.dbo.ItensPedido'; column does not allow nulls. UPDATE fails.
The statement has been terminated.

Já adicionei o AddSingleton:

```` public void ConfigureServices(IServiceCollection services) { services.AddMvc(); services.AddDistributedMemoryCache(); services.AddSession(); services.AddSingleton();

string connectionString = Configuration.GetSection("ConnectionStrings") .GetValue("Default"); services.AddDbContext(options => options.UseSqlServer(connectionString));

services.AddTransient(); } ```