Use error from OnSamlLogin (#30745)

server/i18n/en.json

@@ -3922,6 +3922,10 @@
     "id": "api.user.authorize_oauth_user.response.app_error",
     "translation": "Received invalid response from OAuth service provider."
   },
+  {
+    "id": "api.user.authorize_oauth_user.saml_hook_error.app_error",
+    "translation": "An error occurred in the OnSamlLogin hook. Please contact your System Administrator."
+  },
   {
     "id": "api.user.authorize_oauth_user.saml_response_too_long.app_error",
     "translation": "SAML response is too long"