add DefaultAllowedDataCycleBlocks to prevent NPE

worldedit-core/src/main/java/com/sk89q/worldedit/LocalConfiguration.java

@@ -56,6 +56,7 @@ public abstract class LocalConfiguration {
     public boolean profile = false;
     public boolean traceUnflushedSessions = false;
     public Set<String> disallowedBlocks = new HashSet<>();
+    public Set<String> defaultAllowedDataCycleBlocks = new HashSet<>();
     protected BlockMask disallowedBlocksMask;
     public int defaultChangeLimit = -1;
     public int maxChangeLimit = -1;
@@ -168,6 +169,10 @@ public abstract class LocalConfiguration {
         return blockTypes.stream().filter(Objects::nonNull).map(BlockType::getId).toArray(String[]::new);
     }
 
+    protected String[] getDefaultAllowedDataCycleBlocks() {
+        return new String[0];
+    }
+
     /**
      * Load the configuration.
      */

worldedit-core/src/main/java/com/sk89q/worldedit/util/PropertiesConfiguration.java

@@ -91,7 +91,7 @@ public class PropertiesConfiguration extends LocalConfiguration {
         disallowedBlocks = getStringSet("disallowed-blocks", getDefaultDisallowedBlocks());
         disallowedBlocksMask = null;
         allowedDataCycleBlocks =
-                new HashSet<>(getStringSet("limits.allowed-data-cycle-blocks", null));
+                new HashSet<>(getStringSet("limits.allowed-data-cycle-blocks", getDefaultAllowedDataCycleBlocks()));
         defaultChangeLimit = getInt("default-max-changed-blocks", defaultChangeLimit);
         maxChangeLimit = getInt("max-changed-blocks", maxChangeLimit);
         defaultVerticalHeight = getInt("default-vertical-height", defaultVerticalHeight);