@Builder使用引用时异常

export enum TextSpanType { 
  text, 
  link 
} 
 
export interface TextSpanAttribute { 
  text: string 
  type: TextSpanType, 
} 
 
export class TextSpanList { 
  spans: TextSpanAttribute[] 
 
  constructor(arr: TextSpanAttribute[]) { 
    this.spans = arr 
  } 
} 
 
@Builder 
export function DTTextSpanBuilder($$: TextSpanList) { 
  if ($$.spans !== undefined) { 
    ForEach($$.spans, (item: TextSpanAttribute) => { 
      Span(item.text) 
    }) 
  } 
} 
 
//使用的Commonent代码： 
@Component 
export struct PrivacyPage { 
 
  @State 
  private spans: TextSpanList = new TextSpanList([]) 
 
  aboutToAppear() { 
    setTimeout(() =>{ 
      //循环生成list 
      this.spans = new TextSpanList(list) 
    }, 1000) 
  } 
 
  build() { 
 
    Column() { 
 
      Text() { 
        // 这一段代码能正常生效 
        if (this.spans !== undefined) { 
          ForEach(this.spans.spans, (item: TextSpanAttribute) => { 
            Span(item.text) 
          }) 
        } 
 
        // 这个代码不生效，渲染异常 
        DTTextSpanBuilder(this.spans) 
      } 
    } 
  }