fix(medusa, workflows): Create product workflow with Isolated modules + module registration (#5081)

* fix(medusa, workflows): Isolated modules

* Create polite-kangaroos-rhyme.md

* finalise

* naming

packages/workflows/src/handlers/inventory/attach-inventory-items.ts

@@ -17,7 +17,7 @@ export async function attachInventoryItems({
     .resolve("productVariantInventoryService")
     .withTransaction(manager)
 
-  if (!data?.inventoryItems.length) {
+  if (!data?.inventoryItems?.length) {
     return
   }