fixed empty csv issue

[euanwm]

loading a blank csv no longer crashes the build

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 66.50%. Comparing base (3be4fa5) to head (bccd69d).
Report is 2 commits behind head on development.

Files with missing lines	Patch %	Lines
backend/dbtools/collate.go	0.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #429      +/-   ##
===============================================
- Coverage        66.82%   66.50%   -0.32%     
===============================================
  Files               18       18              
  Lines              627      630       +3     
  Branches             5        5              
===============================================
  Hits               419      419              
- Misses             195      197       +2     
- Partials            13       14       +1     

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