From 746d3776142c9b8072be6e504ba0d34f4ba5dd75 Mon Sep 17 00:00:00 2001
From: Tobias Koppers <tobias.koppers@googlemail.com>
Date: Tue, 22 Sep 2020 16:46:01 +0200
Subject: [PATCH] improve array to set deprecation for access to the first item

---
 lib/util/deprecation.js | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/lib/util/deprecation.js b/lib/util/deprecation.js
index 6348d39ed..224e53482 100644
--- a/lib/util/deprecation.js
+++ b/lib/util/deprecation.js
@@ -134,20 +134,24 @@ exports.arrayToSetDeprecation = (set, name) => {
 		};
 		return fn;
 	};
-	let indexerDefined = 0;
+	const defineIndexGetter = index => {
+		Object.defineProperty(set, index, {
+			get: createIndexGetter(index),
+			set(value) {
+				throw new Error(
+					`${name} was changed from Array to Set (indexing Array with write is not possible)`
+				);
+			}
+		});
+	};
+	defineIndexGetter(0);
+	let indexerDefined = 1;
 	Object.defineProperty(set, "length", {
 		get() {
 			dLength();
 			const length = this.size;
-			for (indexerDefined; indexerDefined < length; indexerDefined++) {
-				Object.defineProperty(set, indexerDefined, {
-					get: createIndexGetter(indexerDefined),
-					set(value) {
-						throw new Error(
-							`${name} was changed from Array to Set (indexing Array with write is not possible)`
-						);
-					}
-				});
+			for (indexerDefined; indexerDefined < length + 1; indexerDefined++) {
+				defineIndexGetter(indexerDefined);
 			}
 			return length;
 		},