Sundry tweaks to aos/vision libs

Change-Id: Ia5578dcf2d42ac53b81af239bf329eb084fcf1d9
diff --git a/aos/vision/events/epoll_events.cc b/aos/vision/events/epoll_events.cc
index e4f789f..d49043c 100644
--- a/aos/vision/events/epoll_events.cc
+++ b/aos/vision/events/epoll_events.cc
@@ -36,7 +36,7 @@
 
     for (int i = 0; i < number_events; i++) {
       EpollEvent *event = static_cast<EpollEvent *>(events[i].data.ptr);
-      if ((events[i].events & ~(EPOLLIN | EPOLLPRI)) != 0) {
+      if ((events[i].events & ~(EPOLLIN | EPOLLPRI | EPOLLERR)) != 0) {
         LOG(FATAL, "unexpected epoll events set in %x on %d\n",
             events[i].events, event->fd());
       }