MapEditor: Error exporting map image when tilesets are null

[TiMMyyMMiT]

MapEditor throws exception and fails to export image or blockset if any of the tilesets are null.
Test on map 49.

java.lang.NullPointerException: Cannot invoke "com.sfc.sf2.graphics.Tile.getRenderPixels(com.sfc.sf2.graphics.TileFlags)" because the return value of "com.sfc.sf2.map.block.MapTile.getTile(com.sfc.sf2.graphics.Tileset[])" is null
	at com.sfc.sf2.map.block.io.MapBlocksetRawImageProcessor.writeTileset(MapBlocksetRawImageProcessor.java:157)
	at com.sfc.sf2.map.block.io.MapBlocksetRawImageProcessor.writeTileset(MapBlocksetRawImageProcessor.java:135)
	at com.sfc.sf2.map.block.io.MapBlocksetRawImageProcessor.packageImageData(MapBlocksetRawImageProcessor.java:113)