From f131c02f88b6001caf48240e95e5d92aed815f60 Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Sat, 23 Nov 2019 11:34:00 +0000
Subject: [PATCH] fpspreadsheet: No "invalid index" error message when
 attempting to save a workbook without reader/writer unit in "uses"

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7197 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/fpspreadsheet/source/common/fpsreaderwriter.pas | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/components/fpspreadsheet/source/common/fpsreaderwriter.pas b/components/fpspreadsheet/source/common/fpsreaderwriter.pas
index 04d0eb3e4..318c08568 100644
--- a/components/fpspreadsheet/source/common/fpsreaderwriter.pas
+++ b/components/fpspreadsheet/source/common/fpsreaderwriter.pas
@@ -1199,7 +1199,8 @@ begin
   begin
     // Bring the priority format to the top
     idx := IndexOf(APriorityFormat);
-    FList.Exchange(0, idx);
+    if idx > -1 then
+      FList.Exchange(0, idx);
   end;
 
   SetLength(Result, FList.Count);
@@ -1224,7 +1225,8 @@ begin
 
   if APriorityFormat <> sfidUnknown then
     // Restore original order
-    FList.Exchange(idx, 0);
+    if idx > -1 then
+      FList.Exchange(idx, 0);
 end;
 
 function TsSpreadFormatRegistry.GetFormatName(AFormatID: TsSpreadFormatID): String;