Fixes sethome in nether and end bug.

https://github.com/BentoBoxWorld/BentoBox/issues/538

src/main/java/world/bentobox/bentobox/api/commands/island/IslandSethomeCommand.java

@@ -22,16 +22,21 @@ public class IslandSethomeCommand extends ConfirmableCommand {
     }
 
     @Override
-    public boolean execute(User user, String label, List<String> args) {
-        // Check island
+    public boolean canExecute(User user, String label, List<String> args) {
+     // Check island
         if (getPlugin().getIslands().getIsland(getWorld(), user.getUniqueId()) == null) {
             user.sendMessage("general.errors.no-island");
             return false;
         }
-        if (!getPlugin().getIslands().userIsOnIsland(getWorld(), user)) {
+        if (!getPlugin().getIslands().userIsOnIsland(user.getWorld(), user)) {
             user.sendMessage("commands.island.sethome.must-be-on-your-island");
             return false;
         }
+        return true;
+    }
+    
+    @Override
+    public boolean execute(User user, String label, List<String> args) {
         if (args.isEmpty()) {
             // island sethome
             setHome(user, 1);

src/main/java/world/bentobox/bentobox/managers/IslandsManager.java

@@ -289,7 +289,7 @@ public class IslandsManager {
 
     /**
      * Gets the island for this player. If they are in a team, the team island is returned.
-     * @param world world to check
+     * @param world world to check. Includes nether and end worlds.
      * @param uuid user's uuid
      * @return Island or null
      */
@@ -736,7 +736,7 @@ public class IslandsManager {
     /**
      * Checks if an online player is in the protected area of an island he owns or he is part of.
      *
-     * @param world the World to check, if null the method will always return {@code false}.
+     * @param world the World to check. Typically this is the user's world. Does not check nether or end worlds. If null the method will always return {@code false}. 
      * @param user the User to check, if null or if this is not a Player the method will always return {@code false}.
      *
      * @return {@code true} if this User is located within the protected area of an island he owns or he is part of,

src/main/java/world/bentobox/bentobox/managers/island/IslandCache.java

@@ -116,8 +116,8 @@ public class IslandCache {
 
     /**
      * Returns island referenced by UUID
-     * @param world world to check
-     * @param uuid player
+     * @param world world to check. Includes nether and end worlds.
+     * @param uuid player's UUID
      * @return island or null if none
      */
     @Nullable