Fails on instances where no MEM is found

[ksahlin]

Thanks for this great piece of software!

I have one bug report and one request

1. slaMEM fails when no mems are found. See e.g., below instance
2. Could slaMEM output exit code 0 when called as slaMEM? It matters when testing builds with travis.

slaMEM -l 17 refs.fa  reads.fa -o outfolder/mems.txt

reads:

>read3
GTAATTACAGGACTTGTGGTTGGTTTTACGATAGCGACTGAACTGCCGAACTTTGTTTAATAATTACACGTTAATCTGGGACAAGCAAGCTGAAGACGCAGTAACAGTTGGTTCTTGCTGAAAGGACCAACCTATGACTTTCTGGTTTTGCCTGTTGTGAACAACGTTACAGTAAAAGGCGGCTTCGTGACTGCTGGTCGAAGAGCCAAATGGTCAACATTAGCATAGCTTGCTTCCTCTTTTTCGTTGCGGAGTTAGCAGGAGAACGTTATGTTTTTACCGAAGAAGGCGCAGTGTTTGCTTGACAATTTACCGTCGTGTCTTCGGTAACAGATATGCTTACCGCTATCCTAACCACCTCAATCACTGCCTTACGGACGTTAACCTAACGCAAATGCCACCAAATACATATGTAAGTCCTCTTAATGTTTGCATGCTTAATCTTTTGATTATTTCCTCTTTCTTTTCTATTTATTAATCCTGTGTCCTCGCCAACCGAATCAACATAAATACGTCAACGAATCAAATGTTGATCTCAAATATCTGTGTCCATGAAATTTCGATCGTAAAAACA
>read4
GGCCTCTAAATTCGGTATCAAGTATTTGCTTCTCCACCGCCAAGCGCACATAAATTCTTTGCGAGTGTTGTTTGGCCACTTTTGGTAGCTCCTGTTTCTTGGCAATTTTGGCTGACACGTTCAGTTTCTTTGCTCCAACTTCGTAAGCAGTTAGTGTAGGCGTGCGGAGGCGTGCGCTACTCGCTACATCGTTGGTTCTACCACCCATATGCCATGGCGTCCTGTAGGTTTGCGCCTAATTACTCGAAGCGCTTTCATTTCTACGAAACGTTTTGGAATAATGTCAACTTGGGCATTGTTGAAACTACGGCTTCCTTAATGCTGACAACCTTGTTTAGTTGTTGTTCTTCCCTTCTTCCAGCATTTAATAACCAGCTTGTTTTAACTCCTTCGCTTTTTCGACTTTCTCCTTCCAGCACCGCAACGTTCTTTTAAGCTACAACGCTTTCTTGAAATCTTCTCGTCATAAA

refs:

>1^1000^1484
AAAGTAATGCCTCTACGTCAGTCGGAACAATGTCGTCGTGTAACTCGACGATCTTAGGAGCTACTAAGGAGAGTCTGTAGGGAACCGACTGGGAAGGTGCCACAAGTTTTCTCTACTACTCCGTCTCCTAAAACAACTCCAAGTGGAAGGTCTGTGGGTTTTTGAGTATAGTCCGTATCTAGACCCAAAAGGGCTTACCTTCGCAATGAAAGAATATCCTTATAGACACGAACGGGAAGAACGGAATCGTTATTAATGACGTCGTACAACGTTTTCCAAGTTCTCCTCTTCCTCCGGATTCGGTTTGGGTTATCTCAACTAGTCCTTTCAAAGACATTGGAGAGTTTCACCTTCCCGTTAAGGTAGAACCCTCAGCATGTTTCACCCCCGGTGACCACTCAGTTACGGAATGTTTTTAAGCCACCTCAGCTAGTGTTCCGAGAGGTGACAGCGACGACGTCCACGTTTGGACTTGTTATCATAA
>1^6337^6813
CATCCTAACATGTTTAGGAACTTCCCCCGAACGTTCGACTCTGAGACACCCCAGGGACCGTACTCTAACTACCTACCTAGTACCCATAGAGAAGTCTTTTGACTTCCAGGCCCTACCACGAGAGGTCTAGTCGAACCTTTACAGGTACTAAAGGTATGTCTACTTTAACTTGTGGAACACCAACTTCTCAACCACTTCTTCTCCCTTCTCACAAACCTACGACATCTTTGATAGTAGTGTTGGTTCAGATATTCATCGTCTGCAGAGTCAGTAAAGTCCTTTGACCAAGGACCCAAACCTTTCCGTATGTGAGAGTAGTTGTTCTGAGAGTACCTTCGTCTACAGGTAATGTTCAGACATTCTCTTACCTTTCTTCACTAGGGTAGATTTCCCACAGACTACCGTCCCCCCTCTACGGTAGGAGTGATGTCACCATATAAGAAGTTACCCTAGTATGACTCAGGTCCCCCACTATC