Fix adding parameter definitions by entity class id

[soininen]

This PR fixes a Traceback that would occur when parameter definitions were added using entity class id instead of name.

Fixes irena-flextool/flextool#228

Checklist before merging

• Documentation (also in Toolbox repo) is up-to-date
• Release notes have been updated
• Unit tests have been added/updated accordingly
• Code has been formatted by black & isort
• Unit tests pass

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.13%. Comparing base (bd929d0) to head (2665daa).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #454   +/-   ##
=======================================
  Coverage   79.13%   79.13%           
=======================================
  Files          77       77           
  Lines       10096    10099    +3     
  Branches     2142     2142           
=======================================
+ Hits         7989     7992    +3     
  Misses       1756     1756           
  Partials      351      351           

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