Block exclusion pattern empty after comma

[attiasas]

• [x] All tests passed. If this feature is not already covered by the tests, I added new tests.

• [x] I used npm run format for formatting the code before submitting the pull request.

  Don't allow exclusion pattern without content after a comma like the following: **/*{test,}* **/*{test,venv,node_modules,target,}*

will end up with pattern: **/**/** for scanners, skipping all files