client/local: use an iterator to stream bus events (#16269)

This means the caller does not have to remember to close the reader, and avoids
having to duplicate the logic to decode JSON into events.

Updates #15160

Change-Id: I20186fabb02f72522f61d5908c4cc80b86b8936b
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

cmd/tailscale/cli/debug.go

@@ -791,21 +791,14 @@ func runDaemonLogs(ctx context.Context, args []string) error {
 }
 
 func runDaemonBusEvents(ctx context.Context, args []string) error {
-	logs, err := localClient.StreamBusEvents(ctx)
-	if err != nil {
-		return err
-	}
-	defer logs.Close()
-	d := json.NewDecoder(bufio.NewReader(logs))
-	for {
-		var line eventbus.DebugEvent
-		err := d.Decode(&line)
+	for line, err := range localClient.StreamBusEvents(ctx) {
 		if err != nil {
 			return err
 		}
 		fmt.Printf("[%d][%q][from: %q][to: %q] %s\n", line.Count, line.Type,
 			line.From, line.To, line.Event)
 	}
+	return nil
 }
 
 var metricsArgs struct {