fix: Throw on cart creation when no region exist (#455)

If you try to create a cart without a region in your setup, we should throw a proper error message.

integration-tests/api/__tests__/store/cart.js

@@ -63,6 +63,24 @@ describe("/store/carts", () => {
       expect(getRes.status).toEqual(200)
     })
 
+    it("fails to create a cart when no region exist", async () => {
+      const api = useApi()
+
+      await dbConnection.manager.query(
+        `UPDATE "country" SET region_id=null WHERE iso_2 = 'us'`
+      )
+      await dbConnection.manager.query(`DELETE from region`)
+
+      try {
+        await api.post("/store/carts")
+      } catch (error) {
+        expect(error.response.status).toEqual(400)
+        expect(error.response.data.message).toEqual(
+          "A region is required to create a cart"
+        )
+      }
+    })
+
     it("creates a cart with country", async () => {
       const api = useApi()
 

packages/medusa/src/api/routes/store/carts/create-cart.js

@@ -82,6 +82,14 @@ export default async (req, res) => {
       if (!value.region_id) {
         const regionService = req.scope.resolve("regionService")
         const regions = await regionService.withTransaction(manager).list({})
+
+        if (!regions?.length) {
+          throw new MedusaError(
+            MedusaError.Types.INVALID_DATA,
+            `A region is required to create a cart`
+          )
+        }
+
         regionId = regions[0].id
       }