Warning: Illegal string offset 'name' in DrupalBootstrapStyles

Scenario: my client has a tight server environment where the server cannot communicate to the internet except to serve pages on port 443 and port 80. (so there's nothing in the server dns cache and port 53 out is blocked)

In this case, CDNs only work for the client, not for the server.

This bug occurs after 3.17 , so 3.18 and higher.

Workaround/Solution:
Add this patch which adds the missing drupal-bootstrap.min.css and also a missing less file that is otherwise provided by server side cdn which doesn't work for servers that cannot access the internet other than serving 443 and 80.

This particular client is using IIS on Windows.

The patch does the job, see the patch.