myokit.save() now raises a ValueError if model, protocol, and script are all None.

[MichaelClerx]

Closes #639.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (f986d25) 100.00% compared to head (34b9723) 100.00%.

❗ Current head 34b9723 differs from pull request most recent head 4ac0b49. Consider uploading reports for the commit 4ac0b49 to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #977   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          102       102           
  Lines        20661     20663    +2     
=========================================
+ Hits         20661     20663    +2     

Impacted Files	Coverage Δ
myokit/_io.py	100.00% <100.00%> (ø)

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