Empty list of processing steps is not parsed correctly
Instead of allowing all the types of processing steps, it seems to be considered as the list of one element, called `'[]'`

Logs:

```
DEBUG: 2023-02-28 19:56:54,650 - root - looking for a job to start, among the following types: ['[]']
DEBUG: 2023-02-28 19:56:54,650 - root - Getting next waiting job for priority Priority.NORMAL, among types ['[]']
```
Empty list of processing steps is not parsed correctly: Instead of allowing all the types of processing steps, it seems to be considered as the list of one element, called `'[]'`

Logs:

```
DEBUG: 2023-02-28 19:56:54,650 - root - looking for a job to start, among the following types: ['[]']
DEBUG: 2023-02-28 19:56:54,650 - root - Getting next waiting job for priority Priority.NORMAL, among types ['[]']
```