change string access

nucleus/gnmi_transport.go

@@ -8,6 +8,7 @@ import (
 	"github.com/openconfig/goyang/pkg/yang"
 	"github.com/openconfig/ygot/ytypes"
 	log "github.com/sirupsen/logrus"
+	"reflect"
 	"strings"
 )
 
@@ -231,7 +232,13 @@ func (g *Gnmi) set(ctx context.Context, setOps []*gnmi.Operation,
 // Subscribe calls GNMI subscribe
 func (g *Gnmi) subscribe(ctx context.Context) error {
 	ctx = gnmi.NewContext(ctx, &g.Options.Config)
-	opts := ctx.Value("opts").(*gnmi.SubscribeOptions)
+	opts, ok := ctx.Value(CtxKeyOpts).(*gnmi.SubscribeOptions)
+	if !ok{
+		return &ErrInvalidTypeAssertion{
+			v: reflect.TypeOf(ctx.Value(CtxKeyOpts)),
+			t: reflect.TypeOf(&gnmi.SubscribeOptions{}),
+		}
+	}
 	go func() {
 		log.WithFields(log.Fields{
 			"address":  opts.Target,