empty error_handler labels (#432)

* Fix and complete error message for empty error_handler labels

* use more specific range for empty label; simpler error message

Co-authored-by: Johannes Koch <johannes.koch@avenga.com>
Co-authored-by: Johannes Koch <53434855+johakoch@users.noreply.github.com>
(cherry picked from commit 353c628)

config/configload/error_handler.go

@@ -70,7 +70,7 @@ func newErrorHandlerContent(content *hcl.BodyContent) (errorHandlerContent, erro
 	}
 
 	for _, block := range content.Blocks.OfType(errorHandler) {
-		kinds, err := newKindsFromLabels(block.Labels)
+		kinds, err := newKindsFromLabels(block)
 		if err != nil {
 			return nil, err
 		}
@@ -107,13 +107,18 @@ func newErrorHandlerContent(content *hcl.BodyContent) (errorHandlerContent, erro
 }
 
 // newKindsFromLabels reads two possible kind formats and returns them per slice entry.
-func newKindsFromLabels(labels []string) ([]string, error) {
+func newKindsFromLabels(block *hcl.Block) ([]string, error) {
 	var allKinds []string
-	for _, kinds := range labels {
+	for _, kinds := range block.Labels {
 		all := strings.Split(kinds, " ")
-		for _, a := range all {
+		for i, a := range all {
 			if a == "" {
-				return nil, errors.Configuration.Messagef("invalid format: %v", labels)
+				err := hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  "empty error_handler label",
+					Subject:  &block.LabelRanges[i],
+				}
+				return nil, errors.Configuration.Message(err.Error())
 			}
 		}
 		allKinds = append(allKinds, all...)

config/configload/error_handler_test.go

@@ -0,0 +1,34 @@
+package configload
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/hcl/v2"
+)
+
+func TestErrorHandler_newKindsFromLabels(t *testing.T) {
+	b := &hcl.Block{
+		Labels: []string{""},
+		LabelRanges: []hcl.Range{
+			hcl.Range{
+				Start: hcl.Pos{
+					Line:   123,
+					Column: 321,
+				},
+				End: hcl.Pos{
+					Line:   123,
+					Column: 323,
+				},
+			},
+		},
+	}
+
+	_, err := newKindsFromLabels(b)
+
+	exp := `message:":123,321-323: empty error_handler label; ", synopsis:"configuration error"`
+	if got := fmt.Sprintf("%#v", err); !strings.Contains(got, exp) {
+		t.Errorf("Unexpected error message given: %s", got)
+	}
+}