Skip quantification if FDR-filtered list is empty

[jonasscheid]

Description of feature

Currently the pipeline crashes with a ambiguous error if the pout_filtered.idXML is empty:

ERROR ~ Error executing process > 'NFCORE_MHCQUANT:MHCQUANT:QUANT:PROCESS_FEATURE:OPENMS_FEATURELINKERUNLABELEDKD (JY_012_5amol)'

Caused by:
  Process `NFCORE_MHCQUANT:MHCQUANT:QUANT:PROCESS_FEATURE:OPENMS_FEATURELINKERUNLABELEDKD (JY_012_5amol)` terminated with an error exit status (139)


Command executed:

  FeatureLinkerUnlabeledKD -in 1_JY_012_5amol.featureXML 2_JY_012_5amol.featureXML 3_JY_012_5amol.featureXML \
      -out JY_012_5amol_all_features_merged.consensusXML \
      -threads 1
  
  cat <<-END_VERSIONS > versions.yml
  "NFCORE_MHCQUANT:MHCQUANT:QUANT:PROCESS_FEATURE:OPENMS_FEATURELINKERUNLABELEDKD":
      openms-thirdparty: $(echo $(FileInfo --help 2>&1) | sed 's/^.*Version: //; s/-.*$//' | sed 's/ -*//; s/ .*$//')
  END_VERSIONS

Command exit status:
  139

Command output:
  Linking 3 featureXMLs.
  Progress of 'reading input':
  
  -- done [took 0.00 s (CPU), 0.03 s (Wall)] -- 

Command error:
  INFO:    Environment variable SINGULARITYENV_TMPDIR is set, but APPTAINERENV_TMPDIR is preferred
  INFO:    Environment variable SINGULARITYENV_NXF_TASK_WORKDIR is set, but APPTAINERENV_NXF_TASK_WORKDIR is preferred
  INFO:    Environment variable SINGULARITYENV_NXF_DEBUG is set, but APPTAINERENV_NXF_DEBUG is preferred
  .command.sh: line 4:    42 Segmentation fault      (core dumped) FeatureLinkerUnlabeledKD -in 1_JY_012_5amol.featureXML 2_JY_012_5amol.featureXML 3_JY_012_5amol.featureXML -out JY_012_5amol_all_features_merged.consensusXML -threads 1

We should throw a proper warning and write an empty file to prevent the pipeline from crashing.

EDIT: We should probably skip quant if pout_filtered post percolator-idfilter is empty, throw warning and default back to ID mode and writing empty output