1 files changed, 8 insertions, 6 deletions
diff --git a/lib/js/urweb.js b/lib/js/urweb.js
index 5482c2a5..2943c897 100644
--- a/lib/js/urweb.js
+++ b/lib/js/urweb.js
@@ -34,7 +34,9 @@ function pf() {
   whine("Pattern match failure");
 }
 
-function runHandlers(ls, arg) {
+function runHandlers(kind, ls, arg) {
+  if (ls == null)
+    alert(kind + ": " + arg);
   for (; ls; ls = ls.next)
     try {
       ls.data(arg)(null);
@@ -48,7 +50,7 @@ function onError(f) {
 }
 
 function er(s) {
-  runHandlers(errorHandlers, s);
+  runHandlers("Error", errorHandlers, s);
   throw {uw_error: s};
 }
 
@@ -61,7 +63,7 @@ function onFail(f) {
 function doExn(v) {
   if (v == null || v.uw_error == null) {
     var s = (v == null ? "null" : v.toString());
-    runHandlers(failHandlers, s);
+    runHandlers("Fail", failHandlers, s);
   }
 }
 
@@ -72,7 +74,7 @@ function onDisconnect(f) {
 }
 
 function discon() {
-  runHandlers(disconnectHandlers, null);
+  runHandlers("Disconnect", disconnectHandlers, null);
 }
 
 var connectHandlers = null;
@@ -82,7 +84,7 @@ function onConnectFail(f) {
 }
 
 function conn() {
-  runHandlers(connectHandlers, null);
+  runHandlers("Connect", connectHandlers, null);
 }
 
 var serverHandlers = null;
@@ -92,7 +94,7 @@ function onServerError(f) {
 }
 
 function servErr(s) {
-  runHandlers(serverHandlers, s);
+  runHandlers("Server", serverHandlers, s);
 }