We see this error all the time
```
no handler registered for event
event.Message=, event.Annotations=, event.Timestamp=0001-01-01T00:00:00Z, event.TaskName=, event.AllocID=, event.TaskID=,
```

So we're handling an even with all default fields. I noted that this can
happen if only err is set as in

```
func (d *driverPluginClient) handleTaskEvents(reqCtx context.Context, ch chan *TaskEvent, stream proto.Driver_TaskEventsClient) {
	defer close(ch)
	for {
		ev, err := stream.Recv()
		if err != nil {
			if err != io.EOF {
				ch <- &TaskEvent{
					Err: grpcutils.HandleReqCtxGrpcErr(err, reqCtx, d.doneCtx),
				}
			}
```

In this case Err fails to be serialized by the logger, see this test

```

	ev := &drivers.TaskEvent{
		Err: fmt.Errorf("errz"),
	}
	i.logger.Warn("ben test", "event", ev)
	i.logger.Warn("ben test2", "event err str", ev.Err.Error())
	i.logger.Warn("ben test3", "event err", ev.Err)
	ev.Err = nil
	i.logger.Warn("ben test4", "nil error", ev....