From 528ebf8d7d978331c04b35ec427fc6e2ab8f33d8 Mon Sep 17 00:00:00 2001
From: Jon Evans <jon@craftyjon.com>
Date: Wed, 6 May 2020 11:50:04 -0400
Subject: [PATCH] Don't try to close empty polygon

Fixes #4337
---
 gerbview/rs274d.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gerbview/rs274d.cpp b/gerbview/rs274d.cpp
index c94541e518..efb1a536bb 100644
--- a/gerbview/rs274d.cpp
+++ b/gerbview/rs274d.cpp
@@ -557,7 +557,10 @@ bool GERBER_FILE_IMAGE::Execute_G_Command( char*& text, int G_command )
         if( m_Exposure && GetLastItemInList() )    // End of polygon
         {
             GERBER_DRAW_ITEM * gbritem = GetLastItemInList();
-            gbritem->m_Polygon.Append( gbritem->m_Polygon.CVertex( 0 ) );
+
+            if( gbritem->m_Polygon.VertexCount() )
+                gbritem->m_Polygon.Append( gbritem->m_Polygon.CVertex( 0 ) );
+
             StepAndRepeatItem( *gbritem );
         }
         m_Exposure = false;