Fixed cache clearing task being cancelled

eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/EcoEnchantsPlugin.java

@@ -101,6 +101,11 @@ public class EcoEnchantsPlugin extends EcoPlugin {
                 }
             }, 1);
         }
+        this.getScheduler().runTimer(() -> {
+            for (EcoEnchant enchant : EcoEnchants.values()) {
+                enchant.clearCachedRequirements();
+            }
+        }, 300, 300);
     }
 
     @Override

eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/EcoEnchant.java

@@ -263,8 +263,7 @@ public abstract class EcoEnchant extends Enchantment implements Listener, Watche
 
         postUpdate();
         this.register();
-        this.cachedRequirements.clear();
-        this.getPlugin().getScheduler().runTimer(this.cachedRequirements::clear, 300, 300);
+        this.clearCachedRequirements();
     }
 
     protected void postUpdate() {
@@ -279,6 +278,13 @@ public abstract class EcoEnchant extends Enchantment implements Listener, Watche
         EnchantmentUtils.register(this);
     }
 
+    /**
+     * Clear requirements cache.
+     */
+    public void clearCachedRequirements() {
+        this.cachedRequirements.clear();
+    }
+
     /**
      * Format the %value% placeholder in description lore.
      *