From e53bd850e77fef9de8853a0d8f96a267db5af039 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Mon, 4 Jan 2016 17:47:32 -0500
Subject: [PATCH] doh

---
 src/Bundle.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Bundle.js b/src/Bundle.js
index a652d90..529f61e 100644
--- a/src/Bundle.js
+++ b/src/Bundle.js
@@ -173,7 +173,7 @@ export default class Bundle {
 			return Promise.resolve( this.resolveId( source, module.id ) )
 				.then( resolvedId => {
 					// If the `resolvedId` is supposed to be external, make it so.
-					const forcedExternal = ~this.external.indexOf( resolvedId.replace( /[\/\\]/g, '/' ) );
+					const forcedExternal = resolvedId && ~this.external.indexOf( resolvedId.replace( /[\/\\]/g, '/' ) );
 
 					if ( !resolvedId || forcedExternal ) {
 						if ( !forcedExternal ) {