Merge pull request prometheus#15216 from yeya24/log-last-series-labels

log last series labelset when hitting OOO series labels

tsdb/index/index.go

@@ -438,7 +438,7 @@ func (w *Writer) AddSeries(ref storage.SeriesRef, lset labels.Labels, chunks ...
 		return err
 	}
 	if labels.Compare(lset, w.lastSeries) <= 0 {
-		return fmt.Errorf("out-of-order series added with label set %q", lset)
+		return fmt.Errorf("out-of-order series added with label set %q, last label set %q", lset, w.lastSeries)
 	}
 
 	if ref < w.lastSeriesRef && !w.lastSeries.IsEmpty() {