Avoid issues with saved games that have no screenshot data

apps/openmw/mwgui/savegamedialog.cpp

@@ -430,7 +430,13 @@ namespace MWGui
 
         // Decode screenshot
         const std::vector<char>& data = mCurrentSlot->mProfile.mScreenshot;
-        Files::IMemStream instream (&data[0], data.size());
+        if (!data.size())
+        {
+            Log(Debug::Warning) << "Warning: Selected saved game has no savegame screenshot";
+            return;
+        }
+
+        Files::IMemStream instream (data.data(), data.size());
 
         osgDB::ReaderWriter* readerwriter = osgDB::Registry::instance()->getReaderWriterForExtension("jpg");
         if (!readerwriter)

components/esm3/savedgame.cpp

@@ -50,7 +50,7 @@ void SavedGame::save (ESMWriter &esm) const
          esm.writeHNString ("DEPE", *iter);
 
     esm.startSubRecord("SCRN");
-    esm.write(&mScreenshot[0], mScreenshot.size());
+    esm.write(mScreenshot.data(), mScreenshot.size());
     esm.endRecord("SCRN");
 }