`checktest` package omits parsing error details

[maratori]

CheckTest.Run fails with a generic error parse failed: invalid proto source and missing details. The original error is ignored by the error reported here.

bufplugin-go/check/checktest/checktest.go

Lines 333 to 336 in 7872400

	Reporter: reporter.NewReporter(
	func(reporter.ErrorWithPos) error {
	return nil
	},

It's very difficult to debug such an error without knowing the actual cause.