Test giving error due to missing file

[miguel76]

The test in fasta-test.js depends on the file test/data/sequences.S.compressed.filtered.fas, which is not in the repository.
Therefore running the test gives an error.
Please note that it is a blocking error, rather than just the test failing.
If the original file is too large to be uploaded to the repo I suggest to upload a small "toy example" FASTA, which would be enough for the test.

The problem can be easily reproduced running yarn test.