move errorParsing.ts to core (#6159)

packages/core/src/utils/quotaErrorDetection.ts

@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { StructuredError } from '../core/turn.js';
+
 export interface ApiError {
   error: {
     code: number;
@@ -13,11 +15,6 @@ export interface ApiError {
   };
 }
 
-interface StructuredError {
-  message: string;
-  status?: number;
-}
-
 export function isApiError(error: unknown): error is ApiError {
   return (
     typeof error === 'object' &&