Skip later steps when no alignment is found

[charles-plessy]

Description of feature

I saw this in another pipeline

  //CheckM2 returns exit code 1 when Diamond doesn't find any hits
    withName: CHECKM2_PREDICT {
        errorStrategy = { task.exitStatus in (130..145) ? 'retry' : task.exitStatus == 1 ? 'ignore' : 'finish' }
    }

Here we could do the same by making the lastal module exit with a given status when no alignment is found (which can be infered from the alignment statistics).

This probably requires to modify the module's source in the nf-core/modules repository, but I open this issue to keep track of the idea.