const sleep=ms=>new Promise(r=>setTimeout(r,ms));
// find header row of detail table, then its scroll body
let hdr=null;
for (const el of document.querySelectorAll('div,table')) {
  const x=(el.innerText||'');
  if (/序号/.test(x) && /错误对象/.test(x) && x.length<200) { hdr=el; break; }
}
if(!hdr) return {err:'no header'};
let box=hdr;
for (let i=0;i<8&&box.parentElement;i++) box=box.parentElement;
const rows=[];
for (const el of box.querySelectorAll('[data-index],tr')) {
  const t=(el.innerText||el.textContent||'').trim().replace(/\s+/g,' ');
  if (t && t.length<400) rows.push(t);
}
return {n: rows.length, rows: rows.slice(0,20), boxLen:(box.innerText||'').length};