webservices: Set event handles to NULL on error.

Signed-off-by: Hans Leidekker <hans@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
diff --git a/dlls/webservices/channel.c b/dlls/webservices/channel.c
index 08e0493..ef37095 100644
--- a/dlls/webservices/channel.c
+++ b/dlls/webservices/channel.c
@@ -166,8 +166,11 @@
 
 error:
     CloseHandle( queue->wait );
+    queue->wait   = NULL;
     CloseHandle( queue->cancel );
+    queue->cancel = NULL;
     CloseHandle( queue->ready );
+    queue->ready  = NULL;
     return hr;
 }