Purpose of this PR

Ensure NetworkVariable.Duplicate() doesn't throw an exception if a value is null

Fixes: #3888

Jira ticket

n/a

Changelog

• Fixed: NestedNetworkVariables initialized with no value no longer throw an error.

Documentation

• No documentation changes or additions were necessary.

Testing & QA (How your changes can be verified during release Playtest)

Functional Testing

Manual testing :

• Manual testing done

Automated tests:

• Covered by existing automated tests
• Covered by new automated tests

Does the change require QA team to:

• Review automated tests?
• Execute manual tests?
• Provide feedback about the PR?

If any boxes above are checked the QA team will be automatically added as a PR reviewer.

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