From c802a0ac96652fc24efce7e35aa87e39c046923f Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Sat, 20 Oct 2018 14:32:59 -0700
Subject: [PATCH] fix crash exposed by examples/dotnet/Program.cs

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
---
 examples/dotnet/Program.cs | 2 +-
 src/model/model.cpp        | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/examples/dotnet/Program.cs b/examples/dotnet/Program.cs
index b6f6e8038..47906add4 100644
--- a/examples/dotnet/Program.cs
+++ b/examples/dotnet/Program.cs
@@ -2103,7 +2103,7 @@ namespace test_mapi
             if (s.Check() != Status.SATISFIABLE)
                 throw new TestFailedException();
 
-            // Console.WriteLine("OK, model: {0}", s.Model.ToString());
+            Console.WriteLine("OK, model: {0}", s.Model.ToString());
         }
 
 
diff --git a/src/model/model.cpp b/src/model/model.cpp
index a1fdfc980..60441054c 100644
--- a/src/model/model.cpp
+++ b/src/model/model.cpp
@@ -312,7 +312,8 @@ void model::collect_occs(top_sort& ts, func_decl* f) {
         func_interp* fi = get_func_interp(f);
         if (fi) {
             e = fi->get_else();
-            collect_occs(ts, e);
+            if (e != nullptr)
+               collect_occs(ts, e);
         }
     }
 }