From 5d49f98d161a8ea8069fcf94e544ecf772957bea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 28 Dec 2023 23:57:13 +0100
Subject: [PATCH] Fixed `self-check` crash

---
 src/compiler/checker.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 934283801b27c..ac8fc8e275461 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2834,8 +2834,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     return findAncestor(errorBindingElement, isBindingElement) !== findAncestor(declaration, isBindingElement) ||
                         declaration.pos < errorBindingElement.pos;
                 }
+                const rootDeclaration = getRootDeclaration(declaration) as Declaration;
+                if (rootDeclaration.kind !== SyntaxKind.VariableDeclaration) {
+                    return true;
+                }
                 // or it might be illegal if usage happens before parent variable is declared (eg var [a] = a)
-                return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage);
+                return isBlockScopedNameDeclaredBeforeUse(rootDeclaration, usage);
             }
             else if (declaration.kind === SyntaxKind.VariableDeclaration) {
                 // still might be illegal if usage is in the initializer of the variable declaration (eg var a = a)