title: Workbox images fetch problem to other Url
body: <p>I am using workbox to fetch images. Images are fetching successfully. but Workbox fetches  image file two times.When I check in console
  1. same image fetch sucessfully
  2. same image throw an error failed to fetch.</p>
  
  <p>and one more erroe (in promise): failed to fetch</p>
  
  <p>My console show::</p>
  
  <p>workbox Router is responding to: <a href="https://www.url.com/images/icon_youtube.png" rel="nofollow noreferrer">https://www.url.com/images/icon_youtube.png</a></p>
  
  <p>uncaught(in promise) TypeError: Failed to fetch</p>
  
  <p>workbox Network request for '<a href="https://www.url.com/images/icon_youtube.png" rel="nofollow noreferrer">https://www.url.com/images/icon_youtube.png</a>' threw an error TypeError:: Failed to fetch</p>