From afa0a31b91b81eaa7ab34a91b4460523d523b1bb Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sat, 24 Jan 2015 16:31:52 +1100
Subject: [PATCH] add no loopParent warning to block scoping transformer

---
 lib/6to5/transformation/transformers/es6/block-scoping.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/6to5/transformation/transformers/es6/block-scoping.js b/lib/6to5/transformation/transformers/es6/block-scoping.js
index ea6d245aab..72a5bd4079 100644
--- a/lib/6to5/transformation/transformers/es6/block-scoping.js
+++ b/lib/6to5/transformation/transformers/es6/block-scoping.js
@@ -454,6 +454,11 @@ LetScoping.prototype.buildHas = function (ret, call) {
   }
 
   if (has.hasBreak || has.hasContinue) {
+    if (!loopParent) {
+      throw new Error("Has no loop parent but we're trying to reassign breaks " +
+                      "and continues, something is going wrong here.");
+    }
+
     // ensure that the parent has a label as we're building a switch and we
     // need to be able to access it
     var label = loopParent.label = loopParent.label || this.scope.generateUidIdentifier("loop");