memories / gallery: multi-select downloads end in "Internal Server Error"

• Impacted Application: murena.iogallery
• Affected application/URL:
• Browser/client and version:

The problem

downloading multiple files in Gallery (memories) via multi-select ends in an error instead of a .zip containing the files.

Steps to reproduce

1. select more than one file via upper left checkmark
2. select download
3. receive .html file instead of .zip that contains the inline text "Internal Server Error"

Video

murena-memories-multiple-files-download-2

(was reported via https://community.e.foundation/t/issue-murena-cloud-photos-not-downloading/77651 )