1 files changed, 23 insertions, 7 deletions

diff --git a/node_modules/source-map-resolve/source-map-resolve.js b/node_modules/source-map-resolve/source-map-resolve.js
index 9979db2e5..387fc1970 100644
--- a/node_modules/source-map-resolve/source-map-resolve.js
+++ b/node_modules/source-map-resolve/source-map-resolve.js
@@ -1,4 +1,4 @@
-// Copyright 2014, 2015, 2016 Simon Lydell
+// Copyright 2014, 2015, 2016, 2017 Simon Lydell
 // X11 (“MIT”) Licensed. (See LICENSE.)
 
 // Note: source-map-resolve.js is generated from source-map-resolve-node.js and
@@ -31,8 +31,9 @@ void (function(root, factory) {
   }
 
   function readSync(read, url, data) {
+    var readUrl = url
     try {
-      return String(read(url))
+      return String(read(readUrl))
     } catch (error) {
       error.sourceMapData = data
       throw error
@@ -51,7 +52,8 @@ void (function(root, factory) {
     if (!mapData || mapData.map) {
       return callbackAsync(callback, null, mapData)
     }
-    read(mapData.url, function(error, result) {
+    var readUrl = mapData.url
+    read(readUrl, function(error, result) {
       if (error) {
         error.sourceMapData = mapData
         return callback(error)
@@ -124,12 +126,17 @@ void (function(root, factory) {
       callback = options
       options = {}
     }
-    var pending = map.sources.length
+    var pending = map.sources ? map.sources.length : 0
     var result = {
       sourcesResolved: [],
       sourcesContent:  []
     }
 
+    if (pending === 0) {
+      callbackAsync(callback, null, result)
+      return
+    }
+
     var done = function() {
       pending--
       if (pending === 0) {
@@ -143,7 +150,8 @@ void (function(root, factory) {
         result.sourcesContent[index] = sourceContent
         callbackAsync(done, null)
       } else {
-        read(fullUrl, function(error, source) {
+        var readUrl = fullUrl
+        read(readUrl, function(error, source) {
           result.sourcesContent[index] = error ? error : String(source)
           done()
         })
@@ -156,20 +164,27 @@ void (function(root, factory) {
       sourcesResolved: [],
       sourcesContent:  []
     }
+
+    if (!map.sources || map.sources.length === 0) {
+      return result
+    }
+
     resolveSourcesHelper(map, mapUrl, options, function(fullUrl, sourceContent, index) {
       result.sourcesResolved[index] = fullUrl
       if (read !== null) {
         if (typeof sourceContent === "string") {
           result.sourcesContent[index] = sourceContent
         } else {
+          var readUrl = fullUrl
           try {
-            result.sourcesContent[index] = String(read(fullUrl))
+            result.sourcesContent[index] = String(read(readUrl))
           } catch (error) {
             result.sourcesContent[index] = error
           }
         }
       }
     })
+
     return result
   }
 
@@ -217,7 +232,8 @@ void (function(root, factory) {
         sourcesRelativeTo: mapUrl,
         map: null
       }
-      read(mapUrl, function(error, result) {
+      var readUrl = mapUrl
+      read(readUrl, function(error, result) {
         if (error) {
           error.sourceMapData = data
           return callback(error)