fix(vhd-lib): don't throw error when a parent locator is missing

CHANGELOG.unreleased.md

@@ -13,6 +13,7 @@
 
 - [Delta Backup Restoration] Fix assertion error [Forum #5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/16)
 - [Delta Backup Restoration] `TypeError: this disposable has already been disposed` [Forum #5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/20)
+- [Delta Backup Restoration] Fix error `ENOENT: no such file '/xo-vm-backups/../parentLocatorEntryN' with vhd having empty parent locator
 
 ### Packages to release
 

packages/vhd-lib/src/Vhd/VhdDirectory.js

@@ -182,7 +182,14 @@ export class VhdDirectory extends VhdAbstract {
   }
 
   async _readParentLocatorData(id) {
-    return (await this._readChunk('parentLocatorEntry' + id)).buffer
+    try {
+      return (await this._readChunk('parentLocatorEntry' + id)).buffer
+    } catch (e) {
+      if (e.code === 'ENOENT') {
+        return Buffer.alloc(0)
+      }
+      throw e
+    }
   }
 
   async _writeParentLocatorData(id, data) {