[2.3.0] Checkmk Werk 17334 created: Catch invalid "Explicit hosts" condition on save instead of crashing

[//]: # (werk v2) # Catch invalid "Explicit hosts" condition on save instead of crashing key | value ---------- | --- date | 2024-10-28T11:23:18+00:00 version | 2.3.0p20 class | fix edition | cre component | wato level | 1 compatible | yes When invalid host names were passed into the "Explicit hosts" condition while creating or editing a rule, Checkmk would crash with the message `Internal error: Invalid hostaddress: '{explicit hosts condition}'. With this werk, the form will warn you that you have entered an invalid *Explicit hosts* condition. This allows you to fix the error without losing the rest of the entered inputs.