fix(xo-server): fix cannot read properties of undefined (#10668)

Introduced by e58587aa1d

CHANGELOG.unreleased.md

@@ -15,6 +15,8 @@
 
 > Users must be able to say: "I had this issue, happy to know it's fixed"
 
+- Fix `cannot read properties of undefined (reading code)` (PR [#10668](https://github.com/vatesfr/xen-orchestra/pull/10668))
+
 ### Packages to release
 
 > When modifying a package, add it here with its release type.
@@ -31,4 +33,6 @@
 
 <!--packages-start-->
 
+- xo-server patch
+
 <!--packages-end-->

packages/xo-server/src/xo-mixins/xen-servers.mjs

@@ -785,7 +785,8 @@ export default class XenServers {
     const lastEventFetchedTimestamp = xapis[server.id]?.lastEventFetchedTimestamp
     if (
       lastEventFetchedTimestamp !== undefined &&
-      Date.now() > lastEventFetchedTimestamp + this._xapiMarkDisconnectedDelay
+      Date.now() > lastEventFetchedTimestamp + this._xapiMarkDisconnectedDelay &&
+      xapis[server.id].watchEventsError !== undefined
     ) {
       server.error = serializeError(xapis[server.id].watchEventsError)
     }