Remove useless err check in LabelValues API (grafana/phlare#669)

Author: 0xPoe

pkg/querier/http.go

@@ -31,19 +31,16 @@ type QueryHandlers struct {
 	upstream querierv1connect.QuerierServiceHandler
 }
 
-// LabelValuesHandler only returns the label values for the given label name.
+// LabelValues only returns the label values for the given label name.
 // This is mostly for fulfilling the pyroscope API and won't be used in the future.
-// /label-values?label=__name__
+// For example, /label-values?label=__name__ will return all the profile types.
 func (q *QueryHandlers) LabelValues(w http.ResponseWriter, req *http.Request) {
 	label := req.URL.Query().Get("label")
 	if label == "" {
 		http.Error(w, "label parameter is required", http.StatusBadRequest)
 		return
 	}
-	var (
-		res []string
-		err error
-	)
+	var res []string
 
 	if label == "__name__" {
 		response, err := q.upstream.ProfileTypes(req.Context(), connect.NewRequest(&querierv1.ProfileTypesRequest{}))
@@ -63,11 +60,6 @@ func (q *QueryHandlers) LabelValues(w http.ResponseWriter, req *http.Request) {
 		res = response.Msg.Names
 	}
 
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
 	w.Header().Add("Content-Type", "application/json")
 	if err := json.NewEncoder(w).Encode(res); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)