refactor: make Structure#deleted a getter to a WeakSet (#7074)

src/structures/GuildMember.js

@@ -7,6 +7,13 @@ const { Error } = require('../errors');
 const GuildMemberRoleManager = require('../managers/GuildMemberRoleManager');
 const Permissions = require('../util/Permissions');
 
+/**
+ * @type {WeakSet<GuildMember>}
+ * @private
+ * @internal
+ */
+const deletedGuildMembers = new WeakSet();
+
 /**
  * Represents a member of a guild on Discord.
  * @implements {TextBasedChannel}
@@ -34,12 +41,6 @@ class GuildMember extends Base {
      */
     this.premiumSinceTimestamp = null;
 
-    /**
-     * Whether the member has been removed from the guild
-     * @type {boolean}
-     */
-    this.deleted = false;
-
     /**
      * The nickname of this member, if they have one
      * @type {?string}
@@ -89,6 +90,19 @@ class GuildMember extends Base {
     return clone;
   }
 
+  /**
+   * Whether or not the structure has been deleted
+   * @type {boolean}
+   */
+  get deleted() {
+    return deletedGuildMembers.has(this);
+  }
+
+  set deleted(value) {
+    if (value) deletedGuildMembers.add(this);
+    else deletedGuildMembers.delete(this);
+  }
+
   /**
    * Whether this GuildMember is a partial
    * @type {boolean}
@@ -384,7 +398,8 @@ class GuildMember extends Base {
 
 TextBasedChannel.applyToClass(GuildMember);
 
-module.exports = GuildMember;
+exports.GuildMember = GuildMember;
+exports.deletedGuildMembers = deletedGuildMembers;
 
 /**
  * @external APIGuildMember