fix(xo-server-backup-reports): fix No recipients defined error (#4998)

Correctly fall back to plugin recipients if `mailRecipients` is empty.

CHANGELOG.unreleased.md

@@ -24,6 +24,7 @@
 - [SDN Controller] Broken encrypted tunnels after host reboot [#4996](https://github.com/vatesfr/xen-orchestra/pull/4996)
 - Don't log server's credentials in case of `SESSION_AUTHENTICATION_FAILED` error (PR [#4995](https://github.com/vatesfr/xen-orchestra/pull/4995))
 - [Plugin/perf-alert] Fix compatibility of the alert messages with XenCenter (PR [#5004](https://github.com/vatesfr/xen-orchestra/pull/5004))
+- [Plugin/backup-reports] Fix `No recipients defined` error when recipients defined at plugin level (PR [#4998](https://github.com/vatesfr/xen-orchestra/pull/4998))
 
 ### Released packages
 
@@ -42,6 +43,7 @@
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
 
+- xo-server-backup-reports patch
 - xo-server-perf-alert patch
 - xen-api patch
 - xo-server-auth-ldap minor

packages/xo-server-backup-reports/src/index.js

@@ -667,13 +667,11 @@ class BackupReportsXoPlugin {
     })
   }
 
-  _sendReport({
-    mailReceivers = this._mailsReceivers,
-    markdown,
-    nagiosMarkdown,
-    subject,
-    success,
-  }) {
+  _sendReport({ mailReceivers, markdown, nagiosMarkdown, subject, success }) {
+    if (mailReceivers === undefined || mailReceivers.length === 0) {
+      mailReceivers = this._mailsReceivers
+    }
+
     const xo = this._xo
     return Promise.all([
       xo.sendEmail !== undefined &&