fixes after my own review (Refs #945)

rpc/client/httpclient.go

@@ -323,6 +323,8 @@ func (w *WSEvents) eventListener() {
 				w.Logger.Error("failed to unmarshal response", "err", err)
 				continue
 			}
+			// NOTE: writing also happens inside mutex so we can't close a channel in
+			// Unsubscribe/UnsubscribeAll.
 			w.mtx.RLock()
 			if ch, ok := w.subscriptions[result.Query]; ok {
 				ch <- result.Data

rpc/core/events.go

@@ -50,10 +50,6 @@ func Subscribe(wsCtx rpctypes.WSRPCContext, query string) (*ctypes.ResultSubscri
 	ctx, cancel := context.WithTimeout(context.Background(), subscribeTimeout)
 	defer cancel()
 	ch := make(chan interface{})
-	es := wsCtx.GetEventSubscriber()
-	if es == nil {
-		es = eventBus
-	}
 	err = eventBusFor(wsCtx).Subscribe(ctx, addr, q, ch)
 	if err != nil {
 		return nil, err