Initial work, copied from the Shopify provider

framework/saleor/utils/handle-fetch-response.ts

@@ -0,0 +1,27 @@
+import { FetcherError } from '@commerce/utils/errors'
+
+export function getError(errors: any[], status: number) {
+  errors = errors ?? [{ message: 'Failed to fetch Saleor API' }]
+  return new FetcherError({ errors, status })
+}
+
+export async function getAsyncError(res: Response) {
+  const data = await res.json()
+  return getError(data.errors, res.status)
+}
+
+const handleFetchResponse = async (res: Response) => {
+  if (res.ok) {
+    const { data, errors } = await res.json()
+
+    if (errors && errors.length) {
+      throw getError(errors, res.status)
+    }
+
+    return data
+  }
+
+  throw await getAsyncError(res)
+}
+
+export default handleFetchResponse