Small fixes

[mosuem]

I also looked into the leaking API symbols:

• ServerHandler is only visible for testing (the next version of the tool will detect this and not complain anymore)
• 'Any' as well now.
• Duration is used in an error constructor, we don't even want to expose that I believe.

So all good.

[github-actions]

PR Health

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
grpc	None	4.0.2	4.0.2-wip	4.0.2	✔️

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

Coverage ✔️

File	Coverage
lib/src/shared/status.dart	💚 59 %

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API leaks ⚠️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols
grpc	Any $1.Duration ServerHandler

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Package publish validation ✔️

Package	Version	Status
package:grpc	4.0.2-wip	WIP (no publish necessary)

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.