[BUG] varying number of columns in output

[bernt-matthias]

Describe the bug

For this request

pysradb search --db sra --query 'NextSeq 500 stress' --source 'transcriptomic' --organism 'Arabidopsis thaliana' --platform 'illumina' --selection 'random' --strategy 'rna seq'  --max 20 --verbosity 3 --stats --saveto 'output.tsv'

I get outputs with different numbers of columns: something between 125 and 129.

Is this expected?

To Reproduce

See above

Desktop (please complete the following information):

• OS: Ubuntu (pysradb installed via conda)
• Python version 3.11.0

Additional context