migrations.AddField(field=models.ForeignObject(...)) doesn't migrate backwards

[BestCrazyNoob]

As per title, migrations that add a ForeignObject to a model crash when migrating backwards.

Example models:

from django.db import models

class A(models.Model):
    x = models.BigIntegerField(
        unique=True,
    )

class B(models.Model):
    x = models.BigIntegerField()
    ref = models.ForeignObject(
        A,
        on_delete=models.DO_NOTHING,
        from_fields=("x"),
        to_fields=("x"),
        null=True,
    )

To reproduce:

• Create A and B with only the field 'x';
• makemigrations && migrate;
• Add the ForeignObject;
• makemigrations && migrate;
• migrate back to the previous state.

Traceback:

  File ".../lib/python3.13/site-packages/django/db/migrations/migration.py", line 193, in unapply
    operation.database_backwards(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        self.app_label, schema_editor, from_state, to_state
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File ".../lib/python3.13/site-packages/django/db/migrations/operations/fields.py", line 128, in database_backwards
    schema_editor.remove_field(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^
        from_model, from_model._meta.get_field(self.name)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File ".../lib/python3.13/site-packages/django/db/backends/sqlite3/schema.py", line 350, in remove_field
    and not (field.remote_field and field.db_constraint)
                                    ^^^^^^^^^^^^^^^^^^^
AttributeError: 'ForeignObject' object has no attribute 'db_constraint'