This fixes errors appearing when running upgrade_d7_field_instance migraiton while it migrate image type fields.

fix-upgrade_d7_field_instance-migration-error.patch

diff --git a/core/modules/field/src/Plugin/migrate/process/d7/FieldInstanceSettings.php b/core/modules/field/src/Plugin/migrate/process/d7/FieldInstanceSettings.php
index 5236e5507a..fcf66af257 100644
--- a/core/modules/field/src/Plugin/migrate/process/d7/FieldInstanceSettings.php
+++ b/core/modules/field/src/Plugin/migrate/process/d7/FieldInstanceSettings.php
@@ -126,6 +126,18 @@ public function transform($value, MigrateExecutableInterface $migrate_executable
           'uuid' => '',
         ];
         break;
+      case 'media_generic':
+        $settings = $instance_settings;
+        if (isset($instance_settings['default_image']) && $instance_settings['default_image'] === 0) {
+          $settings['default_image'] = [
+            'alt' => '',
+            'title' => '',
+            'width' => NULL,
+            'height' => NULL,
+            'uuid' => '',
+          ];
+        }
+        break;
 
       default:
         $settings = $instance_settings;