Fix NPE and plugin not loading when Vault missing

bukkit/src/main/java/me/lucko/luckperms/LPBukkitPlugin.java

@@ -12,14 +12,10 @@ import me.lucko.luckperms.runnables.UpdateTask;
 import me.lucko.luckperms.users.BukkitUserManager;
 import me.lucko.luckperms.users.UserManager;
 import me.lucko.luckperms.utils.LPConfiguration;
-import me.lucko.luckperms.vaulthooks.VaultChatHook;
-import me.lucko.luckperms.vaulthooks.VaultPermissionHook;
-import net.milkbowl.vault.chat.Chat;
-import net.milkbowl.vault.permission.Permission;
+import me.lucko.luckperms.vaulthooks.VaultHook;
 import org.bukkit.Bukkit;
 import org.bukkit.command.PluginCommand;
 import org.bukkit.plugin.PluginManager;
-import org.bukkit.plugin.ServicePriority;
 import org.bukkit.plugin.java.JavaPlugin;
 
 import java.io.File;
@@ -85,18 +81,11 @@ public class LPBukkitPlugin extends JavaPlugin implements LuckPermsPlugin {
         }
 
         // Provide vault support
-        try {
-            if (getServer().getPluginManager().isPluginEnabled("Vault")) {
-                final VaultPermissionHook permsHook = new VaultPermissionHook(this);
-                getServer().getServicesManager().register(Permission.class, permsHook, this, ServicePriority.High);
-                getServer().getServicesManager().register(Chat.class, new VaultChatHook(permsHook), this, ServicePriority.Lowest);
-                getLogger().info("Registered Vault permission & chat hook.");
-            } else {
-                getLogger().info("Vault not found.");
-            }
-        } catch (Exception e) {
-            getLogger().warning("Error whilst hooking into Vault.");
-            e.printStackTrace();
+        if (getServer().getPluginManager().isPluginEnabled("Vault")) {
+            VaultHook.hook(this);
+            getLogger().info("Registered Vault permission & chat hook.");
+        } else {
+            getLogger().info("Vault not found.");
         }
 
     }

bukkit/src/main/java/me/lucko/luckperms/vaulthooks/VaultChatHook.java

@@ -9,9 +9,9 @@ import net.milkbowl.vault.permission.Permission;
  *
  * Registered on the lowest priority so other plugins can override
  */
-public class VaultChatHook extends Chat {
+class VaultChatHook extends Chat {
 
-    public VaultChatHook(Permission perms) {
+    VaultChatHook(Permission perms) {
         super(perms);
     }
 

bukkit/src/main/java/me/lucko/luckperms/vaulthooks/VaultHook.java

@@ -0,0 +1,36 @@
+package me.lucko.luckperms.vaulthooks;
+
+import me.lucko.luckperms.LPBukkitPlugin;
+import net.milkbowl.vault.chat.Chat;
+import net.milkbowl.vault.permission.Permission;
+import org.bukkit.plugin.ServicePriority;
+import org.bukkit.plugin.ServicesManager;
+
+public class VaultHook {
+
+    private static VaultChatHook chatHook = null;
+    private static VaultPermissionHook permissionHook = null;
+
+    public static void hook(LPBukkitPlugin plugin) {
+        try {
+            if (permissionHook == null) {
+                permissionHook = new VaultPermissionHook();
+            }
+            permissionHook.setPlugin(plugin);
+
+            if (chatHook == null) {
+                chatHook = new VaultChatHook(permissionHook);
+            }
+
+            final ServicesManager sm = plugin.getServer().getServicesManager();
+            sm.unregisterAll(plugin);
+            sm.register(Permission.class, permissionHook, plugin, ServicePriority.High);
+            sm.register(Chat.class, chatHook, plugin, ServicePriority.Lowest);
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+
+    }
+
+}

bukkit/src/main/java/me/lucko/luckperms/vaulthooks/VaultPermissionHook.java

@@ -1,6 +1,6 @@
 package me.lucko.luckperms.vaulthooks;
 
-import lombok.AllArgsConstructor;
+import lombok.Setter;
 import me.lucko.luckperms.LPBukkitPlugin;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
 import me.lucko.luckperms.exceptions.ObjectLacksPermissionException;
@@ -8,9 +8,10 @@ import me.lucko.luckperms.groups.Group;
 import me.lucko.luckperms.users.User;
 import net.milkbowl.vault.permission.Permission;
 
-@AllArgsConstructor
-public class VaultPermissionHook extends Permission {
-    private final LPBukkitPlugin plugin;
+class VaultPermissionHook extends Permission {
+
+    @Setter
+    private LPBukkitPlugin plugin;
 
     @Override
     public String getName() {