bwa: conditional definition of the library tag

src/nf_modules/bwa/main.nf

@@ -35,6 +35,10 @@ process mapping_fastq {
   tuple val(file_id), path("${file_id}_bwa_report.txt"), emit: report
 
   script:
+if (file_id.containsKey('library')):
+  library = file_id.library
+else:
+  library = file_id
 bwa_mem_R = "@RG\\tID:${library}\\tSM:${library}\\tLB:lib_${library}\\tPL:illumina"
 """
 bwa mem -t ${task.cpus} \