[beginner's question] What is preventing my package from being deleted?

[Rodrigo Morales]

I defined a package and I installed it. Now, I'm trying to delete that package, 
but the following error is shown:

#+HEADER: :prologue "exec 2>&1"
#+HEADER: :epilogue ":"
#+BEGIN_SRC sh
guix gc -D 
/gnu/store/r7l2scg74yd6pryrs2xbh268akhwl7qi-font-stkaiti-287399335ec1beb72062ce67c36eaa8bec35f386
 ; echo Exit code: $?
#+END_SRC

#+RESULTS:
#+begin_example
finding garbage collector roots...
guix gc: error: cannot delete path 
`/gnu/store/r7l2scg74yd6pryrs2xbh268akhwl7qi-font-stkaiti-287399335ec1beb72062ce67c36eaa8bec35f386'
 since it is still alive
Exit code: 1
#+end_example

I have listed all referrers, but no referrer is shown.

#+HEADER: :prologue "exec 2>&1"
#+HEADER: :epilogue ":"
#+BEGIN_SRC sh
guix gc --referrers 
/gnu/store/r7l2scg74yd6pryrs2xbh268akhwl7qi-font-stkaiti-287399335ec1beb72062ce67c36eaa8bec35f386
 ; echo Exit code: $?
#+END_SRC

#+RESULTS:
#+begin_example
Exit code: 0
#+end_example

My question is: If there are no referres, then what is preventing that package 
from being deleted using =guix gc -D=?