join errors and add index of failed CEL expression

pkg/generators/markers.go

@@ -42,15 +42,21 @@ func (c *CELTag) Validate() error {
 		return fmt.Errorf("empty CEL tag is not allowed")
 	}
 
+	var errs []error
 	if c.Rule == "" {
-		return fmt.Errorf("rule cannot be empty")
+		errs = append(errs, fmt.Errorf("rule cannot be empty"))
 	}
 	if c.Message == "" && c.MessageExpression == "" {
-		return fmt.Errorf("message or messageExpression must be set")
+		errs = append(errs, fmt.Errorf("message or messageExpression must be set"))
 	}
 	if c.Message != "" && c.MessageExpression != "" {
-		return fmt.Errorf("message and messageExpression cannot both be set")
+		errs = append(errs, fmt.Errorf("message and messageExpression cannot be set at the same time"))
+	}
+
+	if len(errs) > 0 {
+		return errors.Join(errs...)
 	}
+
 	return nil
 }
 
@@ -113,8 +119,12 @@ func (c CommentTags) Validate() error {
 		err = errors.Join(err, fmt.Errorf("multipleOf cannot be 0"))
 	}
 
-	for _, celTag := range c.CEL {
-		err = errors.Join(err, celTag.Validate())
+	for i, celTag := range c.CEL {
+		celError := celTag.Validate()
+		if celError == nil {
+			continue
+		}
+		err = errors.Join(err, fmt.Errorf("invalid CEL tag at index %d: %w", i, celError))
 	}
 
 	return err

pkg/generators/markers_test.go

@@ -171,7 +171,7 @@ func TestParseCommentTags(t *testing.T) {
 				`+k8s:validation:cel[2]:rule="self > 5"`,
 				`+k8s:validation:cel[2]:message="must be greater than 5"`,
 			},
-			expectedError: `invalid marker comments: empty CEL tag is not allowed`,
+			expectedError: `invalid marker comments: invalid CEL tag at index 1: empty CEL tag is not allowed`,
 		},
 		{
 			t: types.Float64,