From 7cd779063fc5a66ad1aa0041923371167d87f76d Mon Sep 17 00:00:00 2001
From: Henrik Giesel <hengiesel@gmail.com>
Date: Fri, 23 Apr 2021 18:21:03 +0200
Subject: [PATCH] Fix regression from 70c3b51b0b3c89ebd4f615ab117e

Negative indices were not treated correctly (as offset from end)
---
 ts/editor-toolbar/identifiable.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/ts/editor-toolbar/identifiable.ts b/ts/editor-toolbar/identifiable.ts
index 154895bfc..334222022 100644
--- a/ts/editor-toolbar/identifiable.ts
+++ b/ts/editor-toolbar/identifiable.ts
@@ -8,11 +8,19 @@ function normalize<T extends Identifiable>(
     values: T[],
     idOrIndex: string | number
 ): number {
+    let normalizedIndex: number;
+
     if (typeof idOrIndex === "string") {
-        return values.findIndex((value) => value.id === idOrIndex);
-    } else {
-        return idOrIndex >= values.length ? -1 : idOrIndex;
+        normalizedIndex = values.findIndex((value) => value.id === idOrIndex);
     }
+    else if (idOrIndex < 0) {
+        normalizedIndex = values.length + idOrIndex;
+    }
+    else {
+        normalizedIndex = idOrIndex;
+    }
+
+    return normalizedIndex >= values.length ? -1 : normalizedIndex;
 }
 
 export function search<T extends Identifiable>(