From e26f9940753184cfb5ac111d3b8f42db30414d80 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 29 Mar 2015 17:17:43 +1100
Subject: [PATCH] add existence check when merging source map - fixes #1111

---
 src/babel/transformation/file/index.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/babel/transformation/file/index.js b/src/babel/transformation/file/index.js
index b180a96296..71598a46a7 100644
--- a/src/babel/transformation/file/index.js
+++ b/src/babel/transformation/file/index.js
@@ -535,7 +535,9 @@ export default class File {
       result.code = `${this.shebang}\n${result.code}`;
     }
 
-    result.map = this.mergeSourceMap(result.map);
+    if (result.map) {
+      result.map = this.mergeSourceMap(result.map);
+    }
 
     if (opts.sourceMaps === "inline" || opts.sourceMaps === "both") {
       result.code += "\n" + convertSourceMap.fromObject(result.map).toComment();