Bug with msInsertLayer function

[kwegezeder@…]

The msLayerInsert function could not handle to insert a new layerObj at the last
position of the mapObj's layer array. Like an append. Problem is, that the
msInsertLayer function try to free the layerObj at the new array position. But
this layerObj at the new array position where never initialised and no old
LayerObj was there. The Null-pointer guard in the msFree function fails, because
the pointers of  the layerObj are undefined and not NULL. msFree try to free
uninitialied pointers.

[kwegezeder@…]

Sorry this isn't bug. I haven't seen, that the code:

if (nIndex < 0) { /* Insert at the end by default */
        initLayer(&(map->layers[map->numlayers]), map);
        msCopyLayer(&(map->layers[map->numlayers]), layer);
        map->layerorder[map->numlayers] = map->numlayers;
        map->layers[map->numlayers].index = map->numlayers;
        map->numlayers++;
        return map->numlayers-1;
}

some lines befor protect this problem.