bootstrap public spot test

src/types/shared.ts

@@ -18,14 +18,14 @@ export type numberInString = string;
 export interface APIResponse<T> {
   ret_code: number;
   ret_msg: 'OK' | string;
-  ext_code: string;
-  ext_info: string;
+  ext_code: string | null;
+  ext_info: string | null;
   result: T;
 }
 
 export interface APIResponseWithTime<T> extends APIResponse<T> {
   /** UTC timestamp */
-  time_now: string;
+  time_now: numberInString;
 }
 
 /**