Fix #8074: Prevent infinite spinner when root object provider is missing

[hasip-timurtas]

Summary

This fixes issue #8074 by stopping the loading spinner when the root object provider is missing or unavailable

What Changed

• Enhanced error handling in the MctTree component with try/catch around root and composition loading
• Used finally to always set isLoading to false so the spinner stops
• Checked for missing root objects and added a simple fallback view
• Added warning logs when root objects are missing or have errors

Why It Matters

If the root provider was missing or returned bad data, the tree stayed stuck with a spinner. Now it shows an empty or error state instead 🚀

Testing

• Missing root objects no longer cause an infinite spinner
• Warning logs appear on errors
• Tree shows fallback state when loading fails

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 10 lines in your changes missing coverage. Please review.

Project coverage is 57.10%. Comparing base (f4637b8) to head (257f82f).

Files with missing lines	Patch %	Lines
src/ui/layout/MctTree.vue	33.33%	9 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8104      +/-   ##
==========================================
- Coverage   57.76%   57.10%   -0.66%     
==========================================
  Files         684      684              
  Lines       27560    27571      +11     
  Branches     2701     2702       +1     
==========================================
- Hits        15920    15745     -175     
- Misses      11306    11487     +181     
- Partials      334      339       +5     

Flag	Coverage Δ
e2e-ci	63.23% <ø> (-0.01%)	⬇️
e2e-full	23.88% <ø> (-19.11%)	⬇️
unit	49.02% <33.33%> (-0.22%)	⬇️

Files with missing lines	Coverage Δ
src/ui/layout/MctTree.vue	26.30% <33.33%> (-0.21%)	⬇️

... and 16 files with indirect coverage changes

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