Freyja Error with no error message

[srnarum]

I sometimes get this error, but I can't identify why it is happening.

if [[ $numReads -lt 100 ]]; then
echo INSUFFICIENT DATA > freyja.demix
echo summarized$' '"[('Undetermined', 1.00)]" >> freyja.demix
echo lineages$'mpl'Undetermined >> freyja.demix
echo abundances$'a'1.00 >> freyja.demix
echo resid$' '-1 >> freyja.demix
echo coverage$' '-1 >> freyja.demix

  echo "Undetermined" > freyja_boot_lineages.csv
  touch freyja_bootstrap.png

else
if [[ 6 -lt 4 ]]; then
echo Pileup generation for Freyja...
freyja variants resorted.bam --variants freyja.variants.tsv --depths freyja.depths.tsv --ref /mnt/ceph/srnarum/C-WAP/covidRefSequences/wuhan.fa

      echo Demixing variants by Freyja and bootstrapping
      freyja demix freyja.variants.tsv freyja.depths.tsv --output freyja.demix --confirmedonly &
      freyja boot freyja.variants.tsv freyja.depths.tsv --nt $(nproc) --nb 1000 --output_base freyja_boot
      wait

      echo Parsing bootstrapping output...
      export PYTHONHASHSEED=0
      python3 /mnt/ceph/srnarum/C-WAP/parseFreyjaBootstraps.py freyja.demix freyja_boot_lineages.csv freyja_bootstrap.png
  else
      # Due to a potential bug, some big fastqs result in a pandas error.
      # Generate an empty file to circumvent such failure cases
      echo FATAL ERROR > freyja.demix
      echo summarized$'     '"[('Error', 1.00)]" >> freyja.demix
      echo lineages$'       'Error >> freyja.demix
      echo abundances$'     '1.00 >> freyja.demix
      echo resid$'  '-1 >> freyja.demix
      echo coverage$'       '-1 >> freyja.demix

      echo "ERROR" > freyja_boot_lineages.csv
      touch freyja_bootstrap.png
  fi

fi

Command exit status:

Command output:
(empty)