Add a better message when the download of a model fails

[RHeckerIntel]

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 15 lines in your changes missing coverage. Please review.

Project coverage is 32.00%. Comparing base (6ac0f20) to head (a5b31cb).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/pages/download_model/download_model.dart	0.00%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #113      +/-   ##
==========================================
- Coverage   32.03%   32.00%   -0.03%     
==========================================
  Files         141      140       -1     
  Lines        5704     5706       +2     
==========================================
- Hits         1827     1826       -1     
- Misses       3877     3880       +3     

Flag	Coverage Δ
integrationtests	17.15% <0.00%> (-0.03%)	⬇️
unittests	21.31% <0.00%> (-0.03%)	⬇️

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[Radwan-Ibrahim]

LGTM