Collection's folder.yaml file gets reset when using the importer.

[FumbleGrumble]

Describe the bug After using the importer to import data into a collection, the folder.yaml file for that collection resets to the following

order: date

If the collection is ordered by by alpha or number then going into the cp and navigating to Collections > Products will result in an error "There was a problem fetching your data..." Visiting the front end will result in the following error.

InvalidEntryTypeException in Entry.php line 201:
Entry date not present in a date-based entry: [collections/products/test-product.html]
...

To Reproduce

1. Create a collection, any name, but I will be using "Products"
2. Optional, set collection to sort by alpha or number
3. Take note of the state of /site/content/collections/products/folder.yaml.
4. Import something.

   {
   "collections": {
       "products": {
           "\/products\/test-product-import": {
               "order": "",
               "data": {
                   "title": "Test Product Import"
               }
           }
       }
   }
   }

5. Visit /cp/collections/entries/products for an error "There was a problem fetching your data..."
6. Observe that /site/content/collections/products/folder.yaml has been erased and replaced with order: date as its entire contents.

Expected behavior /site/content/collections/products/folder.yaml shouldn't get overwritten... and everything should work fine.

Environment details:

• Statamic Version 2.11.10
• Fresh Install or Upgrade: Site in development, probably has been updated a few times.
• OS: Windows 7
• Browser: NA
• Web Server: Apache (XAMPP)
• PHP Version: 7.0.27
  • Addons installed: Recaptcha, BigKahuna.

Additional context Problem has been observed across multiple sites in many versions of statamic v2.