fix(xapi/VM_snapshot): handle undefined VM.VUSBs

Fixes zammad#7401

@xen-orchestra/xapi/vm.js

@@ -525,11 +525,15 @@ class Vm {
 
     // requires the VM to be halted because it's not possible to re-plug VUSB on a live VM
     if (unplugVusbs && isHalted) {
-      await asyncMap(vm.VUSBs, async ref => {
-        const vusb = await this.getRecord('VUSB', ref)
-        await vusb.$call('destroy')
-        $defer.call(this, 'call', 'VUSB.create', vusb.VM, vusb.USB_group, vusb.other_config)
-      })
+      // vm.VUSBs can be undefined (e.g. on XS 7.0.0)
+      const vusbs = vm.VUSBs
+      if (vusbs !== undefined) {
+        await asyncMap(vusbs, async ref => {
+          const vusb = await this.getRecord('VUSB', ref)
+          await vusb.$call('destroy')
+          $defer.call(this, 'call', 'VUSB.create', vusb.VM, vusb.USB_group, vusb.other_config)
+        })
+      }
     }
 
     let destroyNobakVdis = false

CHANGELOG.unreleased.md

@@ -15,6 +15,7 @@
 
 - [New SR] Fix `method.startsWith is not a function` when creating an _ext_ SR
 - Import VDI content now works when there is a HTTP proxy between XO and the host (PR [#6261](https://github.com/vatesfr/xen-orchestra/pull/6261))
+- [Backup] Fix `undefined is not iterable (cannot read property Symbol(Symbol.iterator))` on XS 7.0.0
 
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