Efcore: InvalidOperationException when creating a migration and using HasData in OnModelCreating

[filleellif]

When adding a migration using HasData (or rather removing some data) I get an InvalidOperationException: The model must be finalized before 'GetTypeMapping' can be used. Ensure that either 'OnModelCreating' has completed or, if using a stand-alone 'ModelBuilder', that 'FinalizeModel' has been called.

Steps to reproduce

I have simplified it and it's easy to reproduce. I have the following entities:

``` C#
public class SomeEntity
{
public Guid Id { get; set; }
public IEnumerable SubEntities { get; set; }
}

public class AnotherEntity
{
public Guid Id { get; set; }
}

First I add some data in a migration:

``` C#

public class ApplicationDbContext : DbContext
{
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        var id = Guid.NewGuid();

        modelBuilder.Entity<SomeEntity>()
            .HasData(new { Id = id });

        modelBuilder.Entity<AnotherEntity>()
           .HasData(new { Id = Guid.NewGuid(), SomeEntityId = id });
    }
}

This generates a migration perfectly fine.

If I remove the data in another migration so that my DbContext looks like this:

``` C#

public class ApplicationDbContext : DbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
}
}

I get the error shown below:

System.InvalidOperationException: The model must be finalized before 'GetTypeMapping' can be used. Ensure that either 'OnModelCreating' has completed or, if using a stand-alone 'ModelBuilder', that 'FinalizeModel' has been called.
at Microsoft.EntityFrameworkCore.PropertyExtensions.GetTypeMapping(IProperty property)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.RelationshipsSnapshot.SnapshotValue(IPropertyBase propertyBase, Object value)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.RelationshipsSnapshot.SetValue(IPropertyBase propertyBase, Object value)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetRelationshipSnapshotValue(IPropertyBase propertyBase, Object value)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.NavigationFixer.KeyPropertyChanged(InternalEntityEntry entry, IProperty property, IReadOnlyList1 containingPrincipalKeys, IReadOnlyList1 containingForeignKeys, Object oldValue, Object newValue)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntryNotifier.KeyPropertyChanged(InternalEntityEntry entry, IProperty property, IReadOnlyList1 keys, IReadOnlyList1 foreignKeys, Object oldValue, Object newValue)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ChangeDetector.DetectKeyChange(InternalEntityEntry entry, IProperty property)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ChangeDetector.PropertyChanged(InternalEntityEntry entry, IPropertyBase propertyBase, Boolean setModified)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntryNotifier.PropertyChanged(InternalEntityEntry entry, IPropertyBase property, Boolean setModified)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetProperty(IPropertyBase propertyBase, Object value, Boolean isMaterialization, Boolean setModified, Boolean isCascadeDelete, CurrentValueType valueType)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetProperty(IPropertyBase propertyBase, Object value, Boolean isMaterialization, Boolean setModified, Boolean isCascadeDelete)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.CascadeDelete(InternalEntityEntry entry, Boolean force, IEnumerable1 foreignKeys) at Microsoft.EntityFrameworkCore.Update.Internal.UpdateAdapter.CascadeDelete(IUpdateEntry entry, IEnumerable1 foreignKeys)
at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDataOperations(DiffContext diffContext)+MoveNext()
at System.Linq.Enumerable.ConcatIterator1.MoveNext() at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable1 operations, DiffContext diffContext)
at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IModel source, IModel target)
at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
```

Am I missing something or is this a bug in EF Core?

Further technical details

EF Core version: 3.1.3
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 3.1

[filleellif]

I can add that this works fine in EF Core 2.x.

[AndriySvyryd]

Fixed in 3eec55ecf91b0eb3898e8670f297869f92030c55
Unfortunately the fix is too risky to be shipped in a patch release.