fix

src/TerrainTile.cc

@@ -36,9 +36,9 @@ TerrainTile::~TerrainTile()
     if (_data) {
         for (int i = 0; i < _gridSizeLat; i++) {
             delete _data[i];
-            delete _data;
-            _data = NULL;
         }
+        delete _data;
+        _data = NULL;
     }
 }