fix(xapi-explore-sr): fix crash on unreferenced VDI (#10113)

Co-authored-by: Florent BEAUCHAMP <florent.beauchamp@vates.tech>

CHANGELOG.unreleased.md

@@ -46,6 +46,7 @@
 - @xen-orchestra/rest-api minor
 - @xen-orchestra/web patch
 - vhd-lib patch
+- xapi-explore-sr patch
 - xen-api minor
 - xo-server minor
 

packages/xapi-explore-sr/index.mjs

@@ -124,6 +124,9 @@ execPromise(async args => {
       vdi.snapshots,
       ref => {
         const vdi = vdisByRef[ref]
+        if (vdi === undefined) {
+          return
+        }
         if (full || !vdi.sm_config['vhd-parent']) {
           return makeVdiNode(vdi)
         }