### Before filing a report

_Before you file a report, please ensure you are running the latest version of OpenProject and_ 
_have searched for similar bug reports._

### Steps to reproduce

_Please write down the steps to reproduce. Try to write down all necessary preconditions (what permissions do you have, are other users involved?). Example:_

1. Log into OpenProject or auth through the API

2. GET request to `project/{id}/work_packages?select=total` endpoint for a project with 0 work packages (filter dependent - if the filter responses with an empty set, this will reproduce)


### What is the buggy behavior?

_Please describe the bug in as much detail as possible. Example:_

* `?select=total` on empty set will cause the following error / server-side failure:


> {
>  "\_type": "Error",
>  "errorIdentifier": "urn:openproject-org:api:v3:errors:InternalServerError",
>  "message": "An internal error has occurred.undefined method \`\[\]' for nil"
> }

### What is the expected behavior?

_Describe how the application should behave like. Example:_

1. No failure! It should return `{ "total" : 0 }`


### Environment information

_Please check and fill out the following details to help us identify in what versions and distributions of OpenProject the error occurs_

**OpenProject installation type**

* Hosted cloud edition


**Browser**

* [x] 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)

**Language**

_English_ Begin of the insertion

### Hints for QA

* the endpoint to test this is `GET /api/v3/projects/:id/work_packages?select=total`

* it can be executed directly in the browser with the id of any project, that has or has no work packagesEnd of the insertion