From 3c46ed07b6b686783c0f60aa1ec4a89922604a52 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Tue, 7 Jun 2022 12:45:43 -0400
Subject: [PATCH] fix: avoid unnecessarily creating object every time calling
 schema.discriminator() re: #11855

---
 lib/schema.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/schema.js b/lib/schema.js
index c8453fa4307..6464e6c8b52 100644
--- a/lib/schema.js
+++ b/lib/schema.js
@@ -503,7 +503,7 @@ Schema.prototype.defaultOptions = function(options) {
  */
 
 Schema.prototype.discriminator = function(name, schema) {
-  this._applyDiscriminators = Object.assign({}, this._applyDiscriminators, { [name]: schema });
+  this._applyDiscriminators = Object.assign(this._applyDiscriminators || {}, { [name]: schema });
 
   return this;
 };