crash when clicking on the printer icon

I copied my cups configuration from a backup. Of course, `cups` works perfectly fine itself.

However, `switchboard-plug-printer` crashes when I try to open it. Here is the error I get:

```
% switchboard
[INFO 21:35:42.779552] Application.vala:153: Paramètres du système version: 2.0
[INFO 21:35:42.779599] Application.vala:155: Kernel version: 4.13.0-32-generic
**
ERROR:arraylist.c:967:gee_array_list_real_get: assertion failed: (index < _size)
zsh: abort (core dumped) switchboard
```

There is no issue with printing and other dialog boxes like `pantheon-print`, or configuring printers with `system-config-printer`.

---
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