Error message for leaving a required field blank is doubled

**QA System** https://b4.qa.finn.de

### Preconditions:

- Have a work package created

### Steps To Reproduce:

- Add a new work package custom field (**Modules** \> **Administration** \> **Custom field** \>**Work package** tab )
- Select **Required** and **For all project** check-boxes \> **Save**
- Go to a project \> **Work packages**
- Open a work package
- Click **Update**
- Leave the Custom field just added empty
- Click **Submit**

### Actual result:

The error message for the required field that was left blank is doubled
see screen attached

### Expected result:

one error message is enough

Begin of the insertion### Additional info:

The bug can be reproduce also for project custom field, user custom field

End of the insertion **Screenshot:**