from bs4 import BeautifulSoup
from typing import List, Optional

def _collect_html_img_srcs(html: Optional[str]) -> List[str]:
    urls: List[str] = []
    if not html:
        return urls
    try:
        soup = BeautifulSoup(html, "lxml")
        for img in soup.find_all("img"):
            src = img.get("src")
            if src:
                urls.append(src)
    except Exception:
        pass
    return urls
