Improve concrete error message

[damccorm]

In #16776 I introduced CheckConcrete as a better way of passing through an error when a type isn't concrete, but this reference seems to have been missed. This will give the user context on why a type isn't concrete in their error message.

Fixes #18971

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Choose reviewer(s) and mention them in a comment (R: @username).
• Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI.

[damccorm]

R: @jrmccluskey - sending another tiny one your way. You can see that the replacement function is virtually the same as the one being replaced, it just provides the extra context:

beam/sdks/go/pkg/beam/core/typex/class.go

Lines 91 to 106 in 12088cb

	// IsConcrete returns true iff the given type is a valid "concrete" data type. Such
	// data must be fully serializable. Functions and channels are examples of invalid
	// types. Aggregate types with no universals are considered concrete here.
	func IsConcrete(t reflect.Type) bool {
	err := isConcrete(t, make(map[uintptr]bool))
	return err == nil
	}
	// CheckConcrete returns true iff the given type is a valid "concrete" data type and if not,
	// returns false along with an error indicating why the type is not concrete. Concrete
	// data must be fully serializable. Functions and channels are examples of invalid
	// types. Aggregate types with no universals are considered concrete here.
	func CheckConcrete(t reflect.Type) (bool, error) {
	err := isConcrete(t, make(map[uintptr]bool))
	return err == nil, err
	}

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[codecov]

Codecov Report

Merging #22536 (34c08d9) into master (12088cb) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master   #22536   +/-   ##
=======================================
  Coverage   74.17%   74.17%           
=======================================
  Files         706      706           
  Lines       93229    93229           
=======================================
  Hits        69148    69148           
  Misses      22813    22813           
  Partials     1268     1268           

Flag	Coverage Δ
go	51.49% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdks/go/pkg/beam/validate.go	42.10% <0.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us.

[jrmccluskey]

LGTM, good change!