Init should not have an optional json parameter

[0xWDG]

No description provided.

[Copilot]

Pull Request Overview

This PR removes the optional nature of the JSON parameter in DynamicUI initializers and updates type alias names to be more descriptive. The change ensures that DynamicUI always receives valid JSON data at initialization, preventing potential runtime issues from nil JSON.

• Removes default nil values from json parameters in both initializers
• Renames type aliases from Handler/ErrorHandler to Callback/OnError for clarity
• Updates all references to use the new type alias names

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