From 6ab85a42bb4e26d440ae951b239de5c37e928e79 Mon Sep 17 00:00:00 2001
From: Jaco <jacogr@gmail.com>
Date: Wed, 8 Dec 2021 09:26:45 +0100
Subject: [PATCH] assertUnreachable (#1294)

---
 CHANGELOG.md                | 1 +
 packages/util/src/assert.ts | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d37cb0d51..f22ec745e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 Changes:
 
+- Expose `assertUnreachable` for codepaths that should not be followed
 - Swap to upstream `@noble/hashes`
 - Preserve all-caps word splits in `stringCamelCase`
 
diff --git a/packages/util/src/assert.ts b/packages/util/src/assert.ts
index 135f33e9c..2214345d5 100644
--- a/packages/util/src/assert.ts
+++ b/packages/util/src/assert.ts
@@ -42,3 +42,11 @@ export function assertReturn <T> (value: T | undefined | null, message: string |
 
   return value;
 }
+
+/**
+ * @name assertUnreachable
+ * @description An assertion helper that ensures all codepaths are followed
+ */
+export function assertUnreachable (x: never): never {
+  throw new Error(`This codepath should be unreachable. Unhandled input: ${x as unknown as string}`);
+}