Null and missing values

async function safeJson(response) {
  // CDN 404s and the redirect-without-follow are not JSON.
  if (response.status >= 300 && response.status < 400) return null;
  if (!response.headers.get('content-type')?.includes('json')) return null;
  let body;
  try { body = await response.json(); }
  catch { return null; }                     // bad-content-type 404 string
  if (body === null) return null;            // top-level null (Type 3)
  if (Array.isArray(body) && body.length === 0) return [];   // empty array
  if (typeof body === 'object' &&
      Object.keys(body).length === 0) return {};             // empty object
  if (body && typeof body === 'object' &&
      'error' in body && response.status === 200) {
    // 200-with-error-envelope (e.g. POST /search/random with no match)
    return null;
  }
  return body;
}

def safe_json(r):
    """Returns the parsed body or None for any "no useful data" shape."""
    if 300 <= r.status_code < 400:
        return None                                      # redirect — header has the answer
    ct = (r.headers.get("content-type") or "").lower()
    if "json" not in ct:
        return None                                      # CDN 404 string body
    try:
        body = r.json()
    except ValueError:
        return None
    if body is None:
        return None                                      # top-level null
    if isinstance(body, list) and not body:
        return []                                        # empty array
    if isinstance(body, dict):
        if not body:
            return {}                                    # empty object
        if r.status_code == 200 and "error" in body:
            return None                                  # 200-with-error envelope
    return body