v2 DataTable ColGroup in footer/header: Cannot read properties of undefined (reading 'tag')

[klsl2008]

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CodeSandbox Case (Bug Reports)
The example is exactly the one on the documentation: Datatable - ColGroup
CodeSandbox link: Link

Current behavior
The table cannot be rendered correctly with error: Cannot read properties of undefined (reading 'tag')

Expected behavior
The table should be rendered correctly with header and footer.

Minimal reproduction of the problem with instructions
CodeSandbox link: Link

What is the motivation / use case for changing the behavior?

Please tell us about your environment:

• Vue version: 2.6.14 (Nuxt 2.5.18)

• PrimeVue version: 2.9.0

• Browser: [all]