Clean up some io close() calls

src/main/java/com/sk89q/worldedit/data/LegacyChunkStore.java

@@ -120,7 +120,7 @@ public abstract class LegacyChunkStore extends ChunkStore {
 
             return rootTag;
         } finally {
-            stream.close();
+            nbt.close();
         }
     }
 

src/main/java/com/sk89q/worldedit/data/McRegionChunkStore.java

@@ -104,7 +104,7 @@ public abstract class McRegionChunkStore extends ChunkStore {
 
             return rootTag;
         } finally {
-            stream.close();
+            nbt.close();
         }
     }