From 7871bcb4653f15bb6f74654ed256dca3548cddc6 Mon Sep 17 00:00:00 2001
From: Naman-B-Parlecha <namanparlecha@gmail.com>
Date: Tue, 7 Oct 2025 14:20:32 +0530
Subject: [PATCH] fix(convert): error message

Signed-off-by: Naman-B-Parlecha <namanparlecha@gmail.com>
---
 model/histogram/convert.go | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/model/histogram/convert.go b/model/histogram/convert.go
index 250289c8d2..19376db93c 100644
--- a/model/histogram/convert.go
+++ b/model/histogram/convert.go
@@ -15,6 +15,7 @@ package histogram
 
 import (
 	"errors"
+	"fmt"
 	"math"
 
 	"github.com/prometheus/prometheus/model/labels"
@@ -40,8 +41,8 @@ func ConvertNHCBToClassic(nhcb any, lset labels.Labels, lsetBuilder *labels.Buil
 
 	switch h := nhcb.(type) {
 	case *Histogram:
-		if h.Schema != -53 {
-			return errors.New("unsupported histogram schema, only NHCB conversion is supported")
+		if !IsCustomBucketsSchema(h.Schema) {
+			return errors.New("unsupported histogram schema, not a NHCB")
 		}
 		customValues = h.CustomValues
 		positiveBuckets = make([]float64, len(h.PositiveBuckets))
@@ -55,15 +56,15 @@ func ConvertNHCBToClassic(nhcb any, lset labels.Labels, lsetBuilder *labels.Buil
 		count = float64(h.Count)
 		sum = h.Sum
 	case *FloatHistogram:
-		if h.Schema != -53 {
-			return errors.New("unsupported histogram schema, only NHCB conversion is supported")
+		if !IsCustomBucketsSchema(h.Schema) {
+			return errors.New("unsupported histogram schema, not a NHCB")
 		}
 		customValues = h.CustomValues
 		positiveBuckets = h.PositiveBuckets
 		count = h.Count
 		sum = h.Sum
 	default:
-		return errors.New("unsupported histogram type")
+		return fmt.Errorf("unsupported histogram type: %T", h)
 	}
 
 	// Each customValue corresponds to a positive bucket (aligned with the "le" label).