fix(xo-web/backup/restore): dont fail if no backups for a VM (#5156)

Fixes xoa-support#2707

The API does not guarantee that each VM UUID will have at least a backup, and when it happens, the code failed because `first` and `last` where not properly defined.

CHANGELOG.unreleased.md

@@ -11,6 +11,8 @@
 
 > Users must be able to say: “I had this issue, happy to know it's fixed”
 
+- [Backup/Restore] Fixes `an error has occurred` when all backups for a specific VM have been deleted (PR [#5156](https://github.com/vatesfr/xen-orchestra/pull/5156))
+
 ### Packages to release
 
 > Packages will be released in the order they are here, therefore, they should
@@ -27,3 +29,5 @@
 > - major: if the change breaks compatibility
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
+
+- xo-web patch

packages/xo-web/src/xo-app/backup/restore/index.js

@@ -136,6 +136,10 @@ export default class Restore extends Component {
     forEach(backupsByRemote, (backups, remoteId) => {
       const remote = remotes[remoteId]
       forEach(backups, (vmBackups, vmId) => {
+        if (vmBackups.length === 0) {
+          return
+        }
+
         if (backupDataByVm[vmId] === undefined) {
           backupDataByVm[vmId] = { backups: [] }
         }