fix: add null check for document.body when reading scrollHeight

On some pages document.body can be null (non-standard DOM structure or early script execution).
Accessing document.body.scrollHeight caused errors in these cases.

Author: denis-ershov

scrapegraphai/docloaders/chromium.py

@@ -265,7 +265,7 @@ async def ascrape_playwright_scroll(
 
                     while True:
                         current_height = await page.evaluate(
-                            "document.body.scrollHeight"
+                            "document.body ? document.body.scrollHeight : document.documentElement.scrollHeight"
                         )
                         heights.append(current_height)
                         heights = heights[