chrony does not want 0.opnsense.pool.ntp.org to be removed

[erdnuesse]

[X] I have read the contributing guide lines at https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.m
[X] I have searched the existing issues, open and closed, and I'm convinced that mine is new.
[X] The title contains the plugin to which this issue belongs

Describe the bug
During net-wide chrony rollout I discovered the following:
Trying to remove servers from the list seems to be buggy.
As in: removing "0.opnsense.pool.ntp.org" and saving; despite having 6 working alternatives in the list throws:

Input validation
Please correct validation errors in form

• no chance to validate regressions.

To Reproduce
Steps to reproduce the behavior:

1. Go to Services > Chrony > General
2. Click on the X to remove the opnsense entry
3. Save
4. See error
   
   

Expected behavior
Regular save; without error, just no longer the opnsense entry.

Relevant log files
However, I do not see logs regarding the saving of the config, just entries that pushed me to remove the servers in the first place:

2024-10-27T10:56:21	Error	chronyd	NTS-KE session with 17.253.14.251:4460 (0.opnsense.pool.ntp.org) timed out	
2024-10-27T10:49:04	Error	chronyd	Could not connect to 107.189.12.98:4460 (0.opnsense.pool.ntp.org) : Connection refused

No errors in the Web GUI Log either.

Additional context
I'm not saying the validation does not need to be fixed, but I wouldn't have tried if I hadn't seen the errors with the opnsense servers (which may need fixing? idk) in the first place, but that's another story.

However; commenting out
~ # vi /usr/local/etc/chrony.conf
#server 0.opnsense.pool.ntp.org iburst nts
results in chronyd obviously omitting and no longer retrying the opnsense pool, but the web interface still gives me

(I even deleted the line, same result)
And obviously restarted the service each time, also, same result.
It seems to be the validation checking for a specific expected entry; and not accepting alternate servers exclusively. That's as far as I can narrow it down.

Environment
chrony plugin 1.5
OPNsense 24.7.7 amd64; Commit: f20b6eaa5
AMD GX-412TC SOC (4 cores, 4 threads)