Fix incorrect isSingle in ExprBlocksInRegion

Author: APickledWalrus

src/main/java/org/skriptlang/skriptworldguard/elements/expressions/ExprBlocksInRegion.java

@@ -60,6 +60,12 @@ protected Block[] get(Event event, WorldGuardRegion [] regions) {
 		return RegionUtils.getRegionBlockIterator(regionIterator);
 	}
 
+    @Override
+    public boolean isSingle() {
+        // one region has many blocks
+        return false;
+    }
+
 	@Override
 	public Class<? extends Block> getReturnType() {
 		return Block.class;