Crash while scaffolding in EF7 when no primary key set on ManyToMany table

[MariovanZeist]

Assume the following database

CREATE TABLE Blogs (Id int IDENTITY CONSTRAINT [PK_Blogs] PRIMARY KEY,) 
go 

CREATE TABLE Posts (Id int IDENTITY CONSTRAINT [PK_Posts] PRIMARY KEY,) 
go 

CREATE TABLE BlogPosts (
  BlogId int NOT NULL CONSTRAINT [FK_BlogPosts_Blogs] REFERENCES Blogs ON DELETE CASCADE,
  PostId int NOT NULL CONSTRAINT [FK_BlogPosts_Posts] REFERENCES Posts ON DELETE CASCADE,
  -- No Primary key
)
go 

When scaffolding in EF7, scaffolding will fail due to a crash

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpDbContextGenerator.TransformText()
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpModelGenerator.ProcessTemplate(ITextTransformation transformation)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.CSharpModelGenerator.GenerateModel(IModel model, ModelCodeGenerationOptions options)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineerScaffolder.ScaffoldModel(String connectionString, DatabaseModelFactoryOptions databaseOptions, ModelReverseEngineerOptions modelOptions, ModelCodeGenerationOptions codeOptions)
   at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, String dbContextClassName, IEnumerable`1 schemas, IEnumerable`1 tables, String modelNamespace, String contextNamespace, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames, Boolean suppressOnConfiguring, Boolean noPluralize)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 tableFilters, String modelNamespace, String contextNamespace, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames, Boolean suppressOnConfiguring, Boolean noPluralize)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Object reference not set to an instance of an object.

When adding a Primary Key to the Table the configuration will be generated again

EF Core version: 7.0
Database provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer)
Target framework: (e.g. .NET 7.0)
Operating system:
IDE: (e.g. Visual Studio 2022 17.4)

[ajcvickers]

Duplicate of #29516.