feat(exception): 优化错误响应格式。

src/pipelines/dtos/create-pipeline.input.ts

@@ -1,7 +1,7 @@
 import { InputType } from '@nestjs/graphql';
 import { WorkUnitMetadata } from '../../pipeline-tasks/models/work-unit-metadata.model';
 import {
-  IsInstance,
+  IsObject,
   IsOptional,
   IsString,
   IsUUID,
@@ -22,6 +22,6 @@ export class CreatePipelineInput {
   name: string;
 
   @IsOptional()
-  @IsInstance(WorkUnitMetadata)
+  @IsObject()
   workUnitMetadata: WorkUnitMetadata;
 }