fix fencepost error when merging regions

src/mapgen.ts

@@ -574,7 +574,7 @@ function connectRegions(knife: Knife) {
 
     if (Math.random() > EXTRA_CONNECTOR_CHANCE) {
       // at random, don't regard them as merged
-      for (let i = 0; i < knife.region; i++) {
+      for (let i = 0; i <= knife.region; i++) {
         if (sources.indexOf(merged[i]) != -1) {
           merged[i] = dest;
         }