Prism seems to have a weird interaction with Swiper at least in prism-whitespace-mode: when Swiper is invoked with Prism enabled, sometimes Emacs will just beep and show "End of buffer" in the minibuffer. Trying again will usually work. With Prism disabled, Swiper always works.

On Emacs 27.0.90, I can repeat it like this:

1. Start emacs -Q and evaluate:

(package-initialize)
(require 'prism)
(require 'swiper)

2. Open a file in python-mode.
   (2b. Try M-x swiper, note that it works.)
3. Invoke M-x prism-whitespace-mode.
4. Try M-x swiper, note that it dies with "End of buffer".
   (4b. Try M-x swiper again, note that it works most of the time.)

I'm not sure if this is a bug in Prism, Swiper or Emacs. The End of buffer error doesn't seem to trigger debug-on-error. Any ideas on debugging this?