Lectures: Download Complete PDF button not working

[HawKhiem]

Describe the bug

The Download Complete PDF button does not work anymore. I could however still download each file separately. This behavior is only affecting the PSE course, week 10. For other weeks, the button still works fine

To Reproduce

1. Go to PSE (Patterns in Software Engineering)
2. Click on Lectures
3. Click on week 10
4. Click the "Download Complete PDF" button

Expected behavior

The button should work

Screenshots

Which version of Artemis are you seeing the problem on?

7.9.0

What browsers are you seeing the problem on?

Chrome

Additional context

No response

Relevant log output

[laxerhd]

I also have the same issue, when clicking the button I receive an internal server error.

[laxerhd]

The button is working again, do we know why it did not work?
@maximiliansoelch looks like you fixed this in Artemis, this was not a bug in the code, right?