refactor: replace AssertionError with more meaningful exceptions (#5074)
Closes #5074

Replaces `AssertionError` in the following files with more descriptive exceptions:

- `src/datasets/arrow_reader.py`
- `src/datasets/builder.py`
- `src/datasets/utils/version.py`

The issue listed more files that needed to be fixed, but the rest of them were contained in the top-level `datasets` directory, which was removed when #4974 was merged