add unified margin private write tests

src/constants/enum.ts

@@ -16,6 +16,7 @@ export const API_ERROR_CODE = {
   SUCCESS: 0,
   /** This could mean bad request, incorrect value types or even incorrect/missing values */
   PARAMS_MISSING_OR_WRONG: 10001,
+  INVALID_API_KEY_OR_PERMISSIONS: 10003,
   INCORRECT_API_KEY_PERMISSIONS: 10005,
   /** Account not unified margin, update required */
   ACCOUNT_NOT_UNIFIED: 10020,

src/unified-margin-client.ts

@@ -328,7 +328,10 @@ export class UnifiedMarginClient extends BaseRestClient {
     });
   }
 
-  /** Upgrade to unified margin account */
+  /**
+   * Upgrade to unified margin account.
+   * WARNING: This is currently not reversable!
+   */
   upgradeToUnifiedMargin(): Promise<APIResponseV3<any>> {
     return this.postPrivate(
       '/unified/v3/private/account/upgrade-unified-account'