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) {
-    return this.get(name) !== null
+    if (typeof window !== 'undefined') {
+      return this.get(name) !== null
+    }
   }
 
   this.get = function (name) {
-    return window.localStorage.getItem(prefix + name)
+    if (typeof window !== 'undefined') {
+      return window.localStorage.getItem(prefix + name)
+    }
   }
 
   this.set = function (name, content) {
     try {
-      window.localStorage.setItem(prefix + name, content)
+      if (typeof window !== 'undefined') {
+        window.localStorage.setItem(prefix + name, content)
+      }
     } catch (exception) {
       return false
     }
@@ -19,8 +25,10 @@ function Storage (prefix) {
   }
 
   this.remove = function (name) {
-    window.localStorage.removeItem(prefix + name)
-    return true
+    if (typeof window !== 'undefined') {
+      window.localStorage.removeItem(prefix + name)
+      return true
+    }
   }
 
   this.rename = function (originalName, newName) {
@@ -34,7 +42,9 @@ function Storage (prefix) {
 
   function safeKeys () {
     // NOTE: this is a workaround for some browsers
-    return Object.keys(window.localStorage).filter(function (item) { return item !== null && item !== undefined })
+    if (typeof window !== 'undefined') {
+      return Object.keys(window.localStorage).filter(function (item) { return item !== null && item !== undefined })
+    }
   }
 
   this.keys = function () {
@@ -46,16 +56,20 @@ function Storage (prefix) {
   }
 
   // on startup, upgrade the old storage layout
-  safeKeys().forEach(function (name) {
-    if (name.indexOf('sol-cache-file-', 0) === 0) {
-      var content = window.localStorage.getItem(name)
-      window.localStorage.setItem(name.replace(/^sol-cache-file-/, 'sol:'), content)
-      window.localStorage.removeItem(name)
-    }
-  })
-
+  if (typeof window !== 'undefined') {
+    safeKeys().forEach(function (name) {
+      if (name.indexOf('sol-cache-file-', 0) === 0) {
+        var content = window.localStorage.getItem(name)
+        window.localStorage.setItem(name.replace(/^sol-cache-file-/, 'sol:'), content)
+        window.localStorage.removeItem(name)
+      }
+    })
+  }
+  
   // remove obsolete key
-  window.localStorage.removeItem('editor-size-cache')
+  if (typeof window !== 'undefined') {
+    window.localStorage.removeItem('editor-size-cache')
+  }
 }
 
 module.exports = Storage