### Steps to reproduce

1. Login as an admin

2. Go to any project

3. Go to the project Members page

4. Add a placeholder user

5. Once added, click on placeholder user profile


### What is the buggy behaviour?

* error 500


### What is the expected behaviour?

1. Placeholder user profile is opened


### Notes

Normal user profiles open fine

Begin of the insertionOpening placeholder profile also throws an error from Administration > Users

End of the insertion ### Screenshots and other files

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/804394/content">

### Environment information

**OpenProject version**

Core build

[f3a22f2801ab71c7799d4238cd6448fdbfb2a831](https://github.com/opf/openproject/commits/f3a22f2801ab71c7799d4238cd6448fdbfb2a831)

Product version

[5f04a1bfa2cd2861025ca17cfc0b2d4d50043464](https://github.com/opf/saas-openproject/commits/5f04a1bfa2cd2861025ca17cfc0b2d4d50043464)

Core version

OpenProject 17.0.0

**Browser**

* [ ] Chrome
* [x] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)

**Operating System**

* [x] Windows
* [ ] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)