> yassai_identifier(c(V='TRAV2', J='TRAJ61', dna='ATTGTGACTGACACAGGTACAGAATTAATAGGAAATTGGCA', pep='IVTDTGTELIGNW'))
[1] "tg.integer(0)A2A61L13"

Done in 2b8514d18f312f627255b0f2eb0ec1bf4ffa48dd, by return an empty chain instead of integer(0) when receiving an empty chain.

Result after correction:

> yassai_identifier(c(V='TRAV2', J='TRAJ61', dna='ATTGTGACTGACACAGGTACAGAATTAATAGGAAATTGGCA', pep='IVTDTGTELIGNW'))
[1] "tg.A2A61L13"