[BUG] Deleting a certificate without detaching it from the hosts breaks NPM

[Grishkaone]

Describe the bug
I use NPM on a Rasberry Pi. Data is stored in 2 volumes: one for /data and another for /etc/letsencrypt.
I have 13 hosts which are all sub-domains of my main domain.
I generate a Let's Encrypt wildcard certificate with a DNS challenge.
All this worked very well.

I recently changed registrar for my domain. Once the migration was completed with the DNS zones up and running, I had to change the method of generating the wildcard certificate (change of API and identifier).

It's not possible to edit this information in NPM. I therefore deleted the certificate, with a view to creating a new one. The deletion was carried out without error. Afterwards, it was impossible to do anything in the back office. I was unlocated and couldn't relocate. I restarted the container, but nothing changed.

There's an error nginx proxy manager nginx: [emerg] cannot load certificate: what I understand is that the 13 hosts that are still attached to the certificate are trying to load it without success since it's no longer there. I no longer have access to the BO to detach hosts from the certificate.

To get back in control, here are the steps I took:

1. Connect to the container console
2. Open /data/nginx/proxy_host/
3. Delete all *.conf files

Then I was able to reconnect to the BO, the hosts are still there, but no certificates are linked to them.
I could set up my new certificate and attach it to each host one by one. The *.conf files were regenerated at this point.

Nginx Proxy Manager Version
2.11.3

To Reproduce
On a configuration with several hosts attached to a wildcard certificate.

1. Open the SSL Certificates tab
2. Click on the menu to the right of the certificate and select Delete.
3. Confirm deletion.
   NPM becomes unusable.

Expected behavior
I can see several solutions.

1. Prohibit deletion of a certificate attached to an active host. Add a warning when deleting the certificate to indicate that x hosts are bound to this certificate and not allow deletion until they have been manually detached.
2. Automate the process. A message similar to solution 1, but indicating that deletion will automatically detach the certificate from each host beforehand, with a checkbox to indicate agreement.

Screenshots
No screenshot, sorry, everything work fine now.

Operating System
Linux 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
Debian version : 11.11

Additional context
I'm in no hurry to reproduce this problem. I'm not in a position to say whether the fact that it's a wildcard certificate is relevant to causing the bug.
There's another solution that I haven't tried: restore the certificates from a backup of the volume, which should work to restore a functional back office.