chore(core-flows): throw error on invalid promo code (#13140)

* chore(core-flows): throw error on invalid promo code

* add changelog

* better error handling in test

---------

Co-authored-by: william bouchard <williambouchard@williams-MacBook-Pro.local>
Co-authored-by: Carlos R. L. Rodrigues <37986729+carlos-r-l-rodrigues@users.noreply.github.com>

.changeset/ninety-kangaroos-grin.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/core-flows": minor
+---
+
+chore(code-flows): throw error on invalid promo code