OpenAlex scraper bug fix

[ewan-escience]

OpenAlex scraper bug fix

Changes proposed in this pull request

• When trying to scrape zero mentions, return immideately with an empty response to prevent errors later on
• Added tests to test this

How to test

• docker compose down --volumes && docker compose build --parallel && docker compose up --scale data-generation=0
• Now that there are no mentions, run the mentions scraper:
• docker compose exec scrapers java -cp /usr/myjava/scrapers.jar nl.esciencecenter.rsd.scraper.doi.MainMentions
• No errors should be reported
• Same for the citations scraper:
• docker compose exec scrapers java -cp /usr/myjava/scrapers.jar nl.esciencecenter.rsd.scraper.doi.MainCitations

Closes #1317

PR Checklist:

• [ ] Increase version numbers in docker-compose.yml
• [x] Link to a GitHub issue
• [ ] Update documentation
• [x] Tests

[sonarcloud[bot]]

Quality Gate failed for 'scrapers'

Failed conditions
8.5% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud