feat(core-flows, product): options checks on product create/update (#9171)

**What**
- validate that variants are unique with respect to options on product update/create and variant update/create
- validate that the product has options upon creation
- ensure variants have the same number of option values as the product has options
- admin error handling
- update tests

---

FIXES FRMW-2707 CC-556

packages/admin/dashboard/src/routes/product-variants/product-variant-edit/components/product-edit-variant-form/product-edit-variant-form.tsx

@@ -115,6 +115,9 @@ export const ProductEditVariantForm = ({
           handleSuccess("../")
           toast.success(t("products.variant.edit.success"))
         },
+        onError: (error) => {
+          toast.error(error.message)
+        },
       }
     )
   })

packages/admin/dashboard/src/routes/products/product-create-variant/components/create-product-variant-form/create-product-variant-form.tsx

@@ -1,5 +1,5 @@
 import { zodResolver } from "@hookform/resolvers/zod"
-import { Button, ProgressStatus, ProgressTabs } from "@medusajs/ui"
+import { Button, ProgressStatus, ProgressTabs, toast } from "@medusajs/ui"
 import { useFieldArray, useForm, useWatch } from "react-hook-form"
 import { useTranslation } from "react-i18next"
 import { useEffect, useMemo, useState } from "react"
@@ -207,7 +207,7 @@ export const CreateProductVariantForm = ({
     await mutateAsync(
       {
         title,
-        sku,
+        sku: sku || undefined,
         allow_backorder,
         manage_inventory,
         options: data.options,
@@ -249,6 +249,9 @@ export const CreateProductVariantForm = ({
         onSuccess: () => {
           handleSuccess()
         },
+        onError: (error) => {
+          toast.error(error.message)
+        },
       }
     )
   })