Fix issue when trying to access empty gnmi notification in CLI

See merge request !398

cli/cmd/networkElementGet.go

@@ -69,14 +69,18 @@ The network element UUID and request path must be specified as a positional argu
 			panel1 := pterm.DefaultBox.WithTitle("Timestamp:").Sprint(n.GetTimestamp())
 			panel2 := pterm.DefaultBox.WithTitle("Requested Path:").Sprint(args[1])
 
-			val := n.Update[0].GetVal()
-			switch valTyped := val.GetValue().(type) {
-			case *gpb.TypedValue_JsonIetfVal:
-				panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(string(valTyped.JsonIetfVal))
-			case *gpb.TypedValue_JsonVal:
-				panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(string(valTyped.JsonVal))
-			default:
-				panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(protojson.Format(val))
+			if len(n.Update) == 0 {
+				panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint("empty value")
+			} else {
+				val := n.Update[0].GetVal()
+				switch valTyped := val.GetValue().(type) {
+				case *gpb.TypedValue_JsonIetfVal:
+					panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(string(valTyped.JsonIetfVal))
+				case *gpb.TypedValue_JsonVal:
+					panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(string(valTyped.JsonVal))
+				default:
+					panel3 = pterm.DefaultBox.WithTitle("Update:").Sprint(protojson.Format(val))
+				}
 			}
 
 			panels, _ := pterm.DefaultPanel.WithPanels(pterm.Panels{