Describe the bug
If a webtoon isn't long enough to require a scrollbar be generated, you will not be able to turn to scrollwheel to go to the next / previous chapters

To Reproduce
Steps to reproduce the behavior:

1. Open a very short webtoon and make sure there isn't a scrollbar
2. Switch the reading mode to continuous scrolling
3. Scroll in either direction
4. The "Scroll to next / previous chapter" message should not appear

Expected behavior
You should always be able to scroll to go to the next / previous page, no matter the chapter length.

Desktop (please complete the following information):

• OS: Docker
• Browser Firefox
• Version 0.5.6.29

Additional context
Here's a test file. Copy the images to increase the page length
Kavita Testing Ch. 1.zip