Fix iid error handling

[janfb]

• set default None in all potentials
• fix tutorial 05

[michaeldeistler]

Thanks! Maybe I am missing sth, but this seems to be an API change, no?

[michaeldeistler]

Hm why is this needed now? Can we not use x_o from the potential_fn that was used to generate the conditioned_potential_fn?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.34%. Comparing base (299854e) to head (325358e).
Report is 6 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1277       +/-   ##
===========================================
- Coverage   89.24%   78.34%   -10.91%     
===========================================
  Files         119      119               
  Lines        8695     8705       +10     
===========================================
- Hits         7760     6820      -940     
- Misses        935     1885      +950     

Flag	Coverage Δ
unittests	78.34% <100.00%> (-10.91%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...inference/potentials/likelihood_based_potential.py	100.00% <ø> (ø)
.../inference/potentials/posterior_based_potential.py	95.34% <100.00%> (ø)
sbi/inference/potentials/ratio_based_potential.py	100.00% <ø> (ø)
sbi/inference/potentials/score_based_potential.py	97.01% <ø> (ø)

... and 33 files with indirect coverage changes