cat/fastq: update conditional (#2085)

update conditional

modules/cat/fastq/main.nf

@@ -22,7 +22,7 @@ process CAT_FASTQ {
     def prefix = task.ext.prefix ?: "${meta.id}"
     def readList = reads.collect{ it.toString() }
     if (meta.single_end) {
-        if (readList.size > 1) {
+        if (readList.size >= 1) {
             """
             cat ${readList.join(' ')} > ${prefix}.merged.fastq.gz
 
@@ -33,7 +33,7 @@ process CAT_FASTQ {
             """
         }
     } else {
-        if (readList.size > 2) {
+        if (readList.size >= 2) {
             def read1 = []
             def read2 = []
             readList.eachWithIndex{ v, ix -> ( ix & 1 ? read2 : read1 ) << v }