allow default promote image if not set

pages/migrations/0137_alter_rootpage_promote_image.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.0.7 on 2024-07-25 02:04
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pages", "0136_alter_rootpage_layout"),
+        ("wagtailimages", "0025_alter_image_file_alter_rendition_file"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="rootpage",
+            name="promote_image",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                related_name="+",
+                to="wagtailimages.image",
+            ),
+        ),
+    ]

pages/models.py

@@ -147,7 +147,7 @@ class RootPage(Page):
     promote_image = models.ForeignKey(
         'wagtailimages.Image',
         null=True,
-        blank=False,
+        blank=True,
         on_delete=models.SET_NULL,
         related_name='+'
     )