No feedback when --test file.yml fails to parse?

`cwltest [--verbose] --test foo.yml` where `foo.yml` doesn't exist (or doesn't conform to the required schema) fails quietly, with no feedback whatsoever, skipping any valid test items.

- Expected: Failed to find / parse `foo.yml` with non-zero exit flag.
- Nice to have: Descriptive message, failed to parse test with `id: ...` in `foo.yml` because [...]
