Using KeyTransform in ArrayAgg function produces invalid SQL

[Igor Jerosimić]

Using KeyTransform in ordering attribute of ArrayAgg function produces invalid SQL.

# sample model
from django.db import models

class Parent(models.Model):
    name = models.CharField(default='test')

class Child(models.Model):
    parent = models.ForeignKey(
        Parent,
        on_delete=models.SET_NULL,
        related_name='children',
    )
    data = models.JSONField(default=dict)


# sample data
parent = Parent.objects.create()
Child.objects.create(parent=parent, data={'en': 'English', 'fr': 'French'})


# error
Parent.objects.annotate(
        children_array=ArrayAgg(
                KeyTextTransform('en', 'children__data'),
                distinct=True,
                ordering=[KeyTransform('en', 'children__data')],
        ),
).all()

Produces invalid SQL in the ORDER BY section:

ARRAY_AGG(DISTINCT ("children"."data" ->> 'default') ORDER BY None("children"."data"))

NOTE: This was working fine before Django 3.1.