NullReferenceException when deleting optional fields

[Mrjuanblack]

Describe the bug
Hello, I'm getting a NullReferenceException each time I try to create a migration where I delete any optional field from any defined entity.

To Reproduce

1. Have the following entity:

[<CLIMutable>]
type Dossier = {
    [<Key>]
    [<DatabaseGenerated(DatabaseGeneratedOption.Identity)>]
    Id : int
    TypeOfDossier : TypeOfDossier.TypeOfDossier
    InspectionLocation : InspectionLocation.InspectionLocation
    ...
    // Address
    Street : string
    Number : string
    Bus : string option
    PostalCode : string
    City : string
   ...
    OrderConfirmation : string option
    AssigmentConfirmation : string option
    Certificate : string option
    Lab : string option

    OrderConfirmationPhysicallySigned : string option
    AssignmentConfirmationPhysicallySigned : string option

    ManualInvoice: bool
}  

2. Remove OrderConfirmationPhysicallySigned and/or AssignmentConfirmationPhysicallySigned (or any other optional field, I've tried with other optional text fields in other entities too)
3. Create a new migration
4. Get the following error:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Initialize(ColumnOperation columnOperation, IColumn column, RelationalTypeMapping typeMapping, Boolean isNullable, IEnumerable`1 migrationsAnnotations, Boolean inline)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Add(IColumn target, DiffContext diffContext, Boolean inline)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.DiffCollection[T](IEnumerable`1 sources, IEnumerable`1 targets, DiffContext diffContext, Func`4 diff, Func`3 add, Func`3 remove, Func`4[] predicates)+MoveNext()

   at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Diff(ITable source, ITable target, DiffContext diffContext)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.DiffCollection[T](IEnumerable`1 sources, IEnumerable`1 targets, DiffContext diffContext, Func`4 diff, Func`3 add, Func`3 remove, Func`4[] predicates)+MoveNext()

   at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IRelationalModel source, IRelationalModel 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, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>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.

Expected behavior
A new migration without the deleted fields

Additional context
We are using PostgreSQL as our db