Fixes for PR #817

See
https://github.com/feross/webtorrent-desktop/pull/817#discussion-diff-75
968122

src/main/menu.js

@@ -42,13 +42,12 @@ function setWindowFocus (flag) {
 // Disallow opening more screens on top of the current one.
 function setAllowNav (flag) {
   getMenuItem('Preferences').enabled = flag
-  getMenuItem(
-    process.platform === 'darwin'
-      ? 'Create New Torrent...'
-      : 'Create New Torrent from Folder...'
-  ).enabled = flag
-  var item = getMenuItem('Create New Torrent from File...')
-  if (item) item.enabled = flag
+  if (process.platform === 'darwin') {
+    getMenuItem('Create New Torrent...').enabled = flag
+  } else {
+    getMenuItem('Create New Torrent from Folder...').enabled = flag
+    getMenuItem('Create New Torrent from File...').enabled = flag
+  }
 }
 
 function onToggleAlwaysOnTop (flag) {