Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.

## net8环境，我在DataAccess 模块添加efcore Design，再运行项目出现如下错误，但是改成8.0.3就没有问题，我想知道在项目中有没有具体的对应版本，例如net8对应多少的efcore Design，net6 对应多少的efcore Design

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
at WalkingTec.Mvvm.Mvc.FrameworkServiceExtension.AddWtmContext(IServiceCollection services, IConfiguration config, Action`1 options)
at backend.Startup.ConfigureServices(IServiceCollection services) in c:\Users\Demo\Downloads\backend\backend\Startup.cs:line 56
at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Microsoft.AspNetCore.Hosting.ConfigureServicesBuilder.InvokeCore(Object instance, IServiceCollection services)
at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.UseStartup(Type startupType, HostBuilderContext context, IServiceCollection services, Object instance)
at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass7_0.b__0(HostBuilderContext context, IServiceCollection services)
at Microsoft.Extensions.Hosting.HostBuilder.InitializeServiceProvider()
at Microsoft.Extensions.Hosting.HostBuilder.Build()
at backend.Program.Main(String[] args) in c:\Users\Demo\Downloads\backend\backend\Program.cs:line 16

### 安装命令：dotnet add package Microsoft.EntityFrameworkCore --version 8.0.8