Fixed major bug EXT-6092 [crashhunters] Crash in LLFlatListView::selectItemPair

Reason:
 A) incorrect UP arrow handling in accordion control: invisible accordion tab was selected to handle selection.
 B) invalid std::map item (in empty map) was used to make selection in Flat List

Fix: added checks against empty map before use front/back item pair before selecting first/last items.
Also updated processing of the UP key in accordion control to not select invisible accordion tab.

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/318/

--HG--
branch : product-engine

1 files changed, 6 insertions, 0 deletions

diff --git a/indra/llui/llflatlistview.cpp b/indra/llui/llflatlistview.cpp
index 990bf5cd22..e0b2244654 100644
--- a/indra/llui/llflatlistview.cpp
+++ b/indra/llui/llflatlistview.cpp
@@ -744,12 +744,18 @@ LLRect LLFlatListView::getLastSelectedItemRect()
 
 void LLFlatListView::selectFirstItem	()
 {
+	// No items - no actions!
+	if (mItemPairs.empty()) return;
+
 	selectItemPair(mItemPairs.front(), true);
 	ensureSelectedVisible();
 }
 
 void LLFlatListView::selectLastItem		()
 {
+	// No items - no actions!
+	if (mItemPairs.empty()) return;
+
 	selectItemPair(mItemPairs.back(), true);
 	ensureSelectedVisible();
 }