Force pinned_objects to be empty, not null

priv/repo/migrations/20211125110126_force_pinned_objects_to_exist.exs

@@ -0,0 +1,11 @@
+defmodule Pleroma.Repo.Migrations.ForcePinnedObjectsToExist do
+  use Ecto.Migration
+
+  def change do
+    execute("UPDATE users SET pinned_objects = '{}' WHERE pinned_objects IS NULL")
+
+    alter table("users") do
+      modify(:pinned_objects, :map, null: false, default: %{})
+    end
+  end
+end