fix(db-mongodb): handle duplicate unique index error for DocumentDB (#13239)

Currently, with DocumentDB instead of a friendly error like "Value must
be unique" we see a generic "Something went wrong" message.
This PR fixes that by adding a fallback to parse the message instead of
using `error.keyValue` which doesn't exist for responses from
DocumentDB.

packages/db-mongodb/src/utilities/handleError.ts

@@ -2,6 +2,15 @@ import type { PayloadRequest } from 'payload'
 
 import { ValidationError } from 'payload'
 
+function extractFieldFromMessage(message: string) {
+  // eslint-disable-next-line regexp/no-super-linear-backtracking
+  const match = message.match(/index:\s*(.*?)_/)
+  if (match && match[1]) {
+    return match[1] // e.g., returns "email" from "index: email_1"
+  }
+  return null
+}
+
 export const handleError = ({
   collection,
   error,
@@ -18,20 +27,22 @@ export const handleError = ({
   }
 
   // Handle uniqueness error from MongoDB
-  if (
-    'code' in error &&
-    error.code === 11000 &&
-    'keyValue' in error &&
-    error.keyValue &&
-    typeof error.keyValue === 'object'
-  ) {
+  if ('code' in error && error.code === 11000) {
+    let path: null | string = null
+
+    if ('keyValue' in error && error.keyValue && typeof error.keyValue === 'object') {
+      path = Object.keys(error.keyValue)[0] ?? ''
+    } else if ('message' in error && typeof error.message === 'string') {
+      path = extractFieldFromMessage(error.message)
+    }
+
     throw new ValidationError(
       {
         collection,
         errors: [
           {
             message: req?.t ? req.t('error:valueMustBeUnique') : 'Value must be unique',
-            path: Object.keys(error.keyValue)[0] ?? '',
+            path: path ?? '',
           },
         ],
         global,