From 627083fa16f99a7085cdc9e66fb1e0bcb248b95f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dar=C3=ADo=20Javier=20Cravero?= <dario@uxtemple.com>
Date: Thu, 4 Feb 2016 21:54:21 +0000
Subject: [PATCH] fix: don't fail if definition is undefined

Running `uglifyjs --verbose --compress --mangle --screw-ie8 class.js`
with
`class.js`:
```
class Foo {
  bar() {
  }
}
```
Fails with:
```
undefined:4041
  return this.definition().unmangleable(options);
TypeError: Cannot read property 'unmangleable' of undefined
...
```
---
 lib/scope.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/scope.js b/lib/scope.js
index b15d72e4..b2a073e6 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -369,7 +369,8 @@ AST_Scope.DEFMETHOD("references", function(sym){
 });
 
 AST_Symbol.DEFMETHOD("unmangleable", function(options){
-    return this.definition().unmangleable(options);
+    var def = this.definition();
+    return def && def.unmangleable(options);
 });
 
 // property accessors are not mangleable