input: Write a function to implement a web scraper in Python that extracts the top ten trending YouTube videos. The function should make a request to the YouTube trending page, parse the content using BeautifulSoup, and then print the titles of the top ten trending videos. If there are fewer than ten videos found, it should print all available titles. The function should handle cases where the request fails by returning an appropriate error message. 
  
  assert extract_trending_videos() == ["Video 1 Title", "Video 2 Title", "Video 3 Title", "Video 4 Title", "Video 5 Title", "Video 6 Title", "Video 7 Title", "Video 8 Title", "Video 9 Title", "Video 10 Title"]
  assert extract_trending_videos() == ["Video 1 Title", "Video 2 Title", "Video 3 Title", "Video 4 Title", "Video 5 Title"]
  assert extract_trending_videos() == ["Connection error: Unable to reach the YouTube trending page."]
  assert extract_trending_videos() == ["Video Title 1", "Video Title 2", "Video Title 3", "Video Title 4", "Video Title 5", "Video Title 6", "Video Title 7", "Video Title 8", "Video Title 9", "Video Title 10"]
output: def extract_trending_videos():
      try:
          response = requests.get('https://www.youtube.com/feed/trending')
          response.raise_for_status()
          soup = BeautifulSoup(response.text, 'html.parser')
          video_titles = [title.text for title in soup.find_all('a', {'class': 'yt-simple-endpoint style-scope ytd-video-renderer'})[:10]]
          return video_titles if video_titles else ["Connection error: Unable to reach the YouTube trending page."]
      except requests.RequestException:
          return ["Connection error: Unable to reach the YouTube trending page."]