From b1f5933c7dc3d2162cfa89a79c76a7f110c3e0fc Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Thu, 8 Apr 2021 10:30:33 -0700
Subject: [PATCH] fix missing nullptr check for #5156

---
 src/api/api_ast_vector.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/api/api_ast_vector.cpp b/src/api/api_ast_vector.cpp
index 5fe19a7d5..335fb6170 100644
--- a/src/api/api_ast_vector.cpp
+++ b/src/api/api_ast_vector.cpp
@@ -48,7 +48,8 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_ast_vector_dec_ref(c, v);
         RESET_ERROR_CODE();
-        to_ast_vector(v)->dec_ref();
+        if (v) 
+            to_ast_vector(v)->dec_ref();
         Z3_CATCH;
     }