Add default value instead of (undefined) in case of async data loading.

[devahmedsaleh]

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[isilher]

Thank you for creating a PR @eng-ahmedsaleh!

For this particular addition however, I don't think it should be merged. The library expects value to always be set (it is a required param). Defaulting to a fallback (e.g. empty string) should be handled in the async logic that provides the value to the component.

If we would want to have a default fallback for value, it can be set in defaultProps instead of the componentDidMount method.