Fixed crash on incompatible save click (closes #226)

You will see ui_st_error instead of a level name. You still shouldn't
try to load this save.

Author: Xottab-DUTY

src/xrAICore/Navigation/game_graph_inline.h

@@ -107,6 +107,20 @@ IC const GameGraph::_GRAPH_ID& GameGraph::CHeader::vertex_count() const { return
 IC const u32& GameGraph::CHeader::edge_count() const { return (m_edge_count); }
 IC const u32& GameGraph::CHeader::death_point_count() const { return (m_death_point_count); }
 IC const GameGraph::LEVEL_MAP& GameGraph::CHeader::levels() const { return (m_levels); }
+
+IC bool GameGraph::CHeader::level_exist(const _LEVEL_ID& id) const
+{
+    return levels().find(id) != levels().end();
+}
+
+IC bool GameGraph::CHeader::level_exist(pcstr level_name) const
+{
+    for (const auto& level : levels())
+        if (xr_strcmp(level.second.name(), level_name) == 0)
+            return true;
+    return false;
+}
+
 IC const GameGraph::SLevel& GameGraph::CHeader::level(const _LEVEL_ID& id) const
 {
     LEVEL_MAP::const_iterator I = levels().find(id);

src/xrAICore/Navigation/game_graph_space.h

@@ -117,6 +117,8 @@ class CHeader
     IC const u32& death_point_count() const;
     IC const xrGUID& guid() const;
     IC const LEVEL_MAP& levels() const;
+    IC bool level_exist(const _LEVEL_ID& id) const;
+    IC bool level_exist(pcstr level_name) const;
     IC const SLevel& level(const _LEVEL_ID& id) const;
     IC const SLevel& level(LPCSTR level_name) const;
     IC const SLevel* level(LPCSTR level_name, bool) const;

src/xrGame/saved_game_wrapper.cpp

@@ -161,7 +161,10 @@ CSavedGameWrapper::CSavedGameWrapper(LPCSTR saved_game_name)
         {
             CGameGraph graph(*chunk);
             m_level_id = graph.vertex(object->m_tGraphID)->level_id();
-            m_level_name = graph.header().level(m_level_id).name();
+            if (graph.header().level_exist(m_level_id))
+                m_level_name = graph.header().level(m_level_id).name();
+            else
+                m_level_name = CStringTable().translate("ui_st_error");
         }
 
         chunk->close();