update storage.js so no error when the window is not defined

remix-lib/src/storage.js

@@ -2,16 +2,22 @@
 
 function Storage (prefix) {
   this.exists = function (name) {
+    if (typeof window !== 'undefined') {
       return this.get(name) !== null
     }
+  }
 
   this.get = function (name) {
+    if (typeof window !== 'undefined') {
       return window.localStorage.getItem(prefix + name)
     }
+  }
 
   this.set = function (name, content) {
     try {
+      if (typeof window !== 'undefined') {
         window.localStorage.setItem(prefix + name, content)
+      }
     } catch (exception) {
       return false
     }
@@ -19,9 +25,11 @@ function Storage (prefix) {
   }
 
   this.remove = function (name) {
+    if (typeof window !== 'undefined') {
       window.localStorage.removeItem(prefix + name)
       return true
     }
+  }
 
   this.rename = function (originalName, newName) {
     var content = this.get(originalName)
@@ -34,8 +42,10 @@ function Storage (prefix) {
 
   function safeKeys () {
     // NOTE: this is a workaround for some browsers
+    if (typeof window !== 'undefined') {
       return Object.keys(window.localStorage).filter(function (item) { return item !== null && item !== undefined })
     }
+  }
 
   this.keys = function () {
     return safeKeys()
@@ -46,6 +56,7 @@ function Storage (prefix) {
   }
 
   // on startup, upgrade the old storage layout
+  if (typeof window !== 'undefined') {
     safeKeys().forEach(function (name) {
       if (name.indexOf('sol-cache-file-', 0) === 0) {
         var content = window.localStorage.getItem(name)
@@ -53,9 +64,12 @@ function Storage (prefix) {
         window.localStorage.removeItem(name)
       }
     })
+  }
   
   // remove obsolete key
+  if (typeof window !== 'undefined') {
     window.localStorage.removeItem('editor-size-cache')
   }
+}
 
 module.exports = Storage