Ctrl-a Doesn't Work Right

[Addlai]

When org-superstar is enabled with the option org-superstar-remove-leading-stars set to t, Ctrl-a doesn't work correctly.
I suppose this must not be a commonly used option, because breaking Ctrl-a is obviously a rather major bug.

To reproduce:

1. emacs --no-init
2. M-x package-install org-superstar
3. C-x f ... test.org
4. Write the following lines

• Hello
  ** World
  ** !

6. M-x load-file ... .emacs.d/elpa/org-superstar.../org-superstar.el
7. M-x set-variable org-superstar-remove-leading-stars ... t
8. M-x org-superstar-mode
9. Starting at the "Hello" line, press C-n twice, then press C-a.
10. Instead of remaining at the beginning of the line as expected, you end up at the end of the "World" line.