Parents expression shows [object Object] with webpack in uglify

Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 5.4.2
• Cross-platform modules: 5.4.3
• Android Runtime: 5.4.0
• iOS Runtime: Couldn't test this on ios
• Plugin(s): NA

Describe the bug

The parent expression shows [object Object] when the project is ran with --env.uglify flag. For example following code snippet in the Label doesn't work as expected:

<span text="{{$parents['ListView']._people, $parents['ListView']._people.length }}" />

To Reproduce

1. Clone git project https://github.com/rakeshgirase/ParentAabIssue.git.
2. Run the program on android tns run android --env.uglify
3. Please add if this is a same case on ios as well!

Expected behavior
The list should show Person 1 of 12 but it shows Person 1 of [object Object]. Following is how the resulting list looks:

Sample project

https://github.com/rakeshgirase/ParentAabIssue.git

Additional context
If you enable useLegacyWorkflow in nsconfig.json then it works fine. This issue is only in webpack.

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Reproduce the issue by running the linked sample project with tns run android --env.uglify, then compare it with the useLegacyWorkflow setting in nsconfig.json. Trace the webpack/uglify path involved in evaluating the parent expression. Done means the list displays Person 1 of 12 under webpack/uglify as well as the legacy workflow.