bugfix missing oil generator: remove else clause

Closes # (if applicable).

Changes proposed in this Pull Request

[x] I tested my contribution locally and it seems to work fine.
[x] Code and workflow changes are sufficiently documented.
[x] Changed dependencies are added to envs/environment.yaml.
[x] Changes in configuration options are added in all of config.default.yaml.
[x] Changes in configuration options are also documented in doc/configtables/*.csv.
[x] A release note doc/release_notes.rst is added.