HarmonyOS Cannot read property observeComponentCreation2 of undefined

@Builder 
alertBuilder() { 
  Column() { 
 
    Text("欢迎使用abcd").fontSize(17).fontWeight(FontWeight.Medium).margin({top:32}) 
    // Blank("16") 
    Scroll(){ 
      Text(this.desc).fontSize(17).fontWeight(FontWeight.Regular) 
    }.height(199).width("80%") 
    // Blank("19") 
    Button("不同意").backgroundColor(Color.Transparent).fontColor(0x0000000) 
    // Blank("7") 
    Button("同意").backgroundColor(Color.Orange).borderRadius(20).width("80%").margin({bottom:24}).onClick( 
      () => { 
        router.replaceUrl({ 
          url: CommonConstants.MAIN_PAGE_URL 
        }); 
      } 
    ) 
    // Blank() 
 
  } 
}