Public cannot download file preview of unprotected (without password) link share without remote.php

[saw-jan]

Steps to reproduce

1. Create an unprotected (without password) link share of a file (lorem.txt)
2. Try to download the preview of the shared file (without remote.php) ❌

curl 'https://localhost:9200/dav/public-files/ESoiewAIGZCJioP/lorem.txt?preview=1' -vk

< HTTP/1.1 500 Internal Server Error
< Content-Type: application/xml; charset=utf-8
...
<d:error xmlns:d="DAV" xmlns:s="http://sabredav.org/ns">
  <s:exception></s:exception>
  <s:message>{&#34;id&#34;:&#34;com.owncloud.api.thumbnails&#34;,&#34;code&#34;:500,&#34;detail&#34;:&#34;could not get image from source: could not get the image \&#34;https://127.0.0.1:9200/dav/public-files/YMYxKFSIDBqROug/lorem.txt?expiration=\u0026signature=\&#34;. Request returned with statuscode 401 &#34;,&#34;status&#34;:&#34;Internal Server Error&#34;}
  </s:message>
</d:error>

3. Download the preview of the shared file (with remote.php) ✔️

curl 'https://localhost:9200/remote.php/dav/public-files/ESoiewAIGZCJioP/lorem.txt?preview=1' -vk

< HTTP/1.1 200 OK
< Content-Type: image/jpeg