From e807bb0a293e425601886593844737fb6e722b7b Mon Sep 17 00:00:00 2001
From: Juriy Zaytsev <kangax@fb.com>
Date: Tue, 8 Nov 2016 15:50:18 -0800
Subject: [PATCH] Check binding exists

---
 packages/babel-plugin-minify-dead-code-elimination/src/index.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/babel-plugin-minify-dead-code-elimination/src/index.js b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
index 161521cea..ed0c2835b 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/src/index.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
@@ -115,6 +115,8 @@ module.exports = ({ types: t, traverse }) => {
 
           if (param.isIdentifier()) {
             const binding = scope.bindings[param.node.name];
+            if (!binding) continue;
+
             if (binding.referenced) {
               // when the first binding is referenced (right to left)
               // exit without marking anything after this