[listen] Makes error context non-null

[chunhtai]

as title

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[gemini-code-assist]

Code Review

This pull request updates the ErrorCallback signature in the listen package, changing the ErrorContext parameter from an optional named parameter to a required positional parameter. All internal usages and tests are updated to match this new signature, and the package version is bumped to 1.0.0-beta.4. Feedback suggests updating the changelog entry to explicitly mention that ErrorContext is now a required positional parameter to clarify the breaking change.

[gemini-code-assist]

The changelog mentions that ErrorContext is now non-nullable, but it does not mention that it has been changed from an optional named parameter ({ErrorContext? context}) to a required positional parameter (ErrorContext context). Since this is a breaking change that requires updating call sites (removing the context: label), it would be highly beneficial to document this explicitly in the changelog.

Suggested change

	- `ErrorContext` is now a non-nullable parameter.
	- `ErrorContext` is now a required positional, non-nullable parameter.