fix:mirador_crash

[fstoe]

I found out that adding something through the add button in the catalog view which is json but not a manifest makes the viewer crash.
steps to reproduce:

• Open Mirador
• Add Resource with example url: https://iiif.io/api/presentation/2/context.json
• Open legit resource

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

Project coverage is 94.59%. Comparing base (a8daa02) to head (963a934).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
src/state/selectors/manifests.js	66.66%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3927   +/-   ##
=======================================
  Coverage   94.59%   94.59%           
=======================================
  Files         315      315           
  Lines       14773    14776    +3     
  Branches     2491     2494    +3     
=======================================
+ Hits        13974    13977    +3     
  Misses        795      795           
  Partials        4        4           

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[lutzhelm]

Hi @fstoe, could you add a test case for that patch? createManifestoInstance itself is not exported, but getManifestoInstance calls it directly, so this would be a good place to add a test:

https://github.com/ProjectMirador/mirador/blob/master/__tests__/src/selectors/manifests.test.js#L56-L68

Something like

it('does not crash if json is not a manifest', () => {
  const state = { manifests: { x: { json: {} } } };
  const received = getManifestoInstance(state, { manifestId: 'x' });
  expect(received).toBe(undefined);
});

[fstoe]

Hey @lutzhelm,
thanks for the comment. I just added a small test case

Noticed another potential issue in the catalog