###

### Steps to reproduce

1. Create 2 work packages, one parent and one child

2. Note the id of the parent

3. Select them in work packages list (Ctrl/Command + Click to multi-select in work packages list) and select bulk edit

4. In bulk edit, in Parent, enter the id of the parent work package noted before

5. Click Save


### What is the buggy behavior?

* There is an error message which is not really understandable (punctuation is missing):


`You cannot add an ancestor as a descendant Parent cannot be assigned to itself.`

### What is the expected behavior?

1. The error message should be clear and there should be punctuation between the sentences (if both of them are kept)


### Begin of the insertionScreenshots

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/696258/content">

###End of the insertion Environment information

**OpenProject version**

_16.0.1_

**Browser**

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

**Operating System**

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