Merging project manifest to an empty manifest return error

[oh-satyo-iswara]

Describe the bug When merging manifests with one manifest contain no component, merging process returned error Cannot read properties of undefined (reading 'constructor')

To Reproduce Steps to reproduce the behavior:

1. Create 2 package manifest. a. nonEmpty-package.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
  <types>
    <name>CustomField</name>
    <members>Account.Test__c</members>
  </types>
  <version>55.0</version>
</Package>

b. empty-package.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
  <Package xmlns="http://soap.sforce.com/2006/04/metadata">
  <version>55.0</version>
</Package>

2. run sfdx sfpowerkit:project:manifest:merge -p nonEmpty-package.xml,empty-package.xml -d ./out
3. Result : error with message ERROR running sfpowerkit:project:manifest:merge: Cannot read properties of undefined (reading 'constructor')

Expected behavior out/package.xml contains the same component as nonEmpty-package.xml

Screenshots N/A

Desktop (please complete the following information):

• OS: MacOX
• Node Version : v16.14.2
• Version of sfpowerkit : 6.0.0
• Salesforce Org Version - v55.0

Additional context N/A

[oh-satyo-iswara]

Suggestion for fix on src/commands/sfpowerkit/project/manifest/merge.ts add checking on metadataTypes (metadataTypes !== undefined) in processMainfest method.

[Caitlyn-Mills]

Can I ask what the use case is for merging with an empty package.xml?

[oh-satyo-iswara]

Yes, the use case is as a part of our CI, at the beginning of each sprint, we start with empty package.xml which developer start merging into.