From 94c34e0132a851e26e605bc3a0ddd3f7f1fafdec Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Tue, 16 Jun 2015 01:53:53 +0100
Subject: [PATCH] throw error when attemping to replace a Program root node
 with another node not of type Program - closes #1762

---
 src/babel/traversal/path/replacement.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/babel/traversal/path/replacement.js b/src/babel/traversal/path/replacement.js
index d8ec9dc01c..3f425b891e 100644
--- a/src/babel/traversal/path/replacement.js
+++ b/src/babel/traversal/path/replacement.js
@@ -93,9 +93,13 @@ export function replaceWith(replacement, whateverAllowed) {
   }
 
   // normalise inserting an entire AST
-  if (t.isProgram(replacement)) {
+  if (t.isProgram(replacement) && !this.isProgram()) {
     replacement = replacement.body;
     whateverAllowed = true;
+  } else {
+    if (this.isProgram()) {
+      throw new Error("You can only replace a Program root node with another Program node");
+    }
   }
 
   if (Array.isArray(replacement)) {