Fix chunk snapshot generation (needed for Dynmap)

src/main/java/org/bukkit/craftbukkit/CraftChunk.java

@@ -168,7 +168,8 @@ public class CraftChunk implements Chunk {
 
                 // Copy base IDs
                 for (int j = 0; j < 4096; j++) {
-                    IBlockData blockData = net.minecraft.server.Block.getByCombinedId(baseids[j]);
+                    if (baseids[j] == 0) continue;
+                    IBlockData blockData = (IBlockData) net.minecraft.server.Block.d.a(baseids[j]);
                     blockids[j] = (short) net.minecraft.server.Block.getId(blockData.getBlock());
                     int data = blockData.getBlock().toLegacyData(blockData);
                     int jj = j >> 1;