Fix/cascading product variant deletion (#570)

* testing for deletes of variants when a product is deleted

* remove variants with products

* test using direct db query

* formatting

* removed unused imports

packages/medusa/src/services/product.js

@@ -468,7 +468,10 @@ class ProductService extends BaseService {
       const productRepo = manager.getCustomRepository(this.productRepository_)
 
       // Should not fail, if product does not exist, since delete is idempotent
-      const product = await productRepo.findOne({ where: { id: productId } })
+      const product = await productRepo.findOne(
+        { id: productId },
+        { relations: ["variants"] }
+      )
 
       if (!product) return Promise.resolve()