Feature/exe 2054 bail early on bad demux

[johandahlberg]

Description

Exit with status 1 if less them 50% of reads are demuxed.

Fixes: exe-2054

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

With the added unit test.

PR checklist:

• This comment contains a description of changes (with reason).
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• If a new tool or package is included, I have updated poetry.lock, and cited it properly
• I have checked my code and documentation and corrected any misspellings
• I have documented any significant changes to the code in CHANGELOG.md