From 6af6617e36cefe2838ccc9d165dd79f8a5d449ef Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Sat, 27 Apr 2019 10:39:44 -0700
Subject: [PATCH] fix #2248

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
---
 src/smt/theory_seq_empty.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/smt/theory_seq_empty.h b/src/smt/theory_seq_empty.h
index 93b4be173..81f1af06f 100644
--- a/src/smt/theory_seq_empty.h
+++ b/src/smt/theory_seq_empty.h
@@ -117,6 +117,7 @@ namespace smt {
             }
             if (u.is_seq(s, ch)) {
                 expr* v = m_model.get_fresh_value(ch);
+				if (!v) return nullptr;
                 return u.str.mk_unit(v);
             }
             UNREACHABLE();