refactor: reduce nesting in SyncUserEmailToMember.sync_email

Extract apply_sync/1 and sync_by_record_type/4 to satisfy Credo max depth 2.

lib/mv/email_sync/changes/sync_user_email_to_member.ex

@@ -44,24 +44,27 @@ defmodule Mv.EmailSync.Changes.SyncUserEmailToMember do
   defp sync_email(changeset) do
     Ash.Changeset.around_transaction(changeset, fn cs, callback ->
       result = callback.(cs)
+      apply_sync(result)
+    end)
+  end
 
+  defp apply_sync(result) do
     with {:ok, record} <- Helpers.extract_record(result),
          {:ok, user, member} <- get_user_and_member(record) do
-        # When called from Member-side, we need to update the member in the result
-        # When called from User-side, we update the linked member in DB only
-        case record do
-          %Mv.Membership.Member{} ->
-            # Member-side: Override member email in result with user email
-            Helpers.override_with_linked_email(result, user.email)
-
-          %Mv.Accounts.User{} ->
-            # User-side: Sync user email to linked member in DB
-            Helpers.sync_email_to_linked_record(result, member, user.email)
-        end
+      sync_by_record_type(result, record, user, member)
     else
       _ -> result
     end
-    end)
+  end
+
+  # When called from Member-side, we update the member in the result.
+  # When called from User-side, we sync user email to the linked member in DB.
+  defp sync_by_record_type(result, %Mv.Membership.Member{}, user, _member) do
+    Helpers.override_with_linked_email(result, user.email)
+  end
+
+  defp sync_by_record_type(result, %Mv.Accounts.User{}, user, member) do
+    Helpers.sync_email_to_linked_record(result, member, user.email)
   end
 
   # Retrieves user and member - works for both resource types