From 17d3e36bd6492ad8e16cf4a93daac8c81d121917 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Wed, 12 Aug 2020 12:36:40 +0100
Subject: [PATCH] Fix crash bug when condition expression is empty.

---
 common/libeval_compiler/libeval_compiler.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/common/libeval_compiler/libeval_compiler.cpp b/common/libeval_compiler/libeval_compiler.cpp
index 139e378846..c322ef7416 100644
--- a/common/libeval_compiler/libeval_compiler.cpp
+++ b/common/libeval_compiler/libeval_compiler.cpp
@@ -626,7 +626,12 @@ bool COMPILER::generateUCode( UCODE* aCode, CONTEXT* aPreflightContext )
                        return visitedNodes.find( node ) != visitedNodes.end();
                    };
 
-    assert( m_tree );
+    if( !m_tree )
+    {
+        // Empty expression returns true
+        aCode->AddOp( makeUop( TR_UOP_PUSH_VALUE, 1.0 ) );
+        return true;
+    }
 
     stack.push_back( m_tree );