Add util to combine multiple errors so everyone checkable (#22473)

Signed-off-by: yah01 <yang.cen@zilliz.com>

internal/util/errutil/errors.go

@@ -0,0 +1,37 @@
+package errutil
+
+import "github.com/cockroachdb/errors"
+
+type multiErrors struct {
+	errs []error
+}
+
+func (e multiErrors) Unwrap() error {
+	if len(e.errs) <= 1 {
+		return nil
+	}
+	return multiErrors{
+		errs: e.errs[1:],
+	}
+}
+
+func (e multiErrors) Error() string {
+	final := e.errs[0]
+	for i := 1; i < len(e.errs); i++ {
+		final = errors.Wrap(e.errs[i], final.Error())
+	}
+	return final.Error()
+}
+
+func (e multiErrors) Is(err error) bool {
+	return errors.IsAny(err, e.errs...)
+}
+
+func Combine(errs ...error) error {
+	if len(errs) == 0 {
+		return nil
+	}
+	return multiErrors{
+		errs,
+	}
+}

internal/util/errutil/errors_test.go

@@ -0,0 +1,31 @@
+package errutil
+
+import (
+	"testing"
+
+	"github.com/cockroachdb/errors"
+	"github.com/stretchr/testify/suite"
+)
+
+type ErrSuite struct {
+	suite.Suite
+}
+
+func (s *ErrSuite) TestCombine() {
+	var (
+		errFirst  = errors.New("first")
+		errSecond = errors.New("second")
+		errThird  = errors.New("third")
+	)
+
+	err := Combine(errFirst, errSecond)
+	s.True(errors.Is(err, errFirst))
+	s.True(errors.Is(err, errSecond))
+	s.False(errors.Is(err, errThird))
+
+	s.Equal("first: second", err.Error())
+}
+
+func TestErrors(t *testing.T) {
+	suite.Run(t, new(ErrSuite))
+}