From 8c6165d8033ba99c029c1cef4c09fc1f5f17ad3b Mon Sep 17 00:00:00 2001
From: Daniel Kroening <kroening@cs.ox.ac.uk>
Date: Sat, 21 Apr 2018 13:09:38 +0100
Subject: [PATCH] precondition for get_json_stream()

---
 src/util/ui_message.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/util/ui_message.h b/src/util/ui_message.h
index 62756df777e..a9becebbf48 100644
--- a/src/util/ui_message.h
+++ b/src/util/ui_message.h
@@ -52,6 +52,7 @@ class ui_message_handlert : public message_handlert
 
   json_stream_arrayt &get_json_stream() override
   {
+    PRECONDITION(json_stream!=nullptr);
     return *json_stream;
   }