--- libev/ev_epoll.c	2019/06/25 16:43:52	1.75
+++ libev/ev_epoll.c	2019/06/26 00:01:46	1.76
@@ -130,6 +130,8 @@
 
       return;
     }
+  else
+    assert (("libev: I/O watcher with invalid fd found in epoll_ctl", errno != EBADF && errno != ELOOP && errno != EINVAL));
 
   fd_kill (EV_A_ fd);