Certain attachment types don't show an icon in the search (quick nav) dropdown

Steps to reproduce:
1. Attach a .jar file to a Confluence page
2. You'll see an icon (specifically for .jar files) on the view attachments page
3. Search for the file you've just attached, and wait for the autocomplete dropdown to appear below the search box
4. The attached file will appear in the dropdown but shows blank space where its icon should be

.jar files might not be the only types of attachments that this issue can be reproduced for - please check all possible attachment types.

I could consistently reproduce this across all browsers.