fix fastp to allow exporting of only *.merged.fastq.gz (#1325)

* fix: remove left-over unnecessary code

* Update main.nf

* Update meta.yml

modules/fastp/main.nf

@@ -13,7 +13,7 @@ process FASTP {
     val   save_merged
 
     output:
-    tuple val(meta), path('*.trim.fastq.gz')  , emit: reads
+    tuple val(meta), path('*.trim.fastq.gz')  , optional:true, emit: reads
     tuple val(meta), path('*.json')           , emit: json
     tuple val(meta), path('*.html')           , emit: html
     tuple val(meta), path('*.log')            , emit: log

modules/fastp/meta.yml

@@ -22,6 +22,12 @@ input:
       description: |
         List of input FastQ files of size 1 and 2 for single-end and paired-end data,
         respectively.
+  - save_trimmed_fail:
+      type: boolean
+      description: Specify true to save files that failed to pass trimming thresholds ending in `*.fail.fastq.gz`
+  - save_merged:
+      type: boolean
+      description: Specify true to save all merged reads to the a file ending in `*.merged.fastq.gz`
 
 output:
   - meta: