fix: error message handling and isolation in repositories

[cofin]

Correct error message retrieval and ensure that error message overrides are isolated for different repository instances. This improves the clarity and reliability of error messages across the application.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.32%. Comparing base (3dc01e2) to head (b90a965).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
advanced_alchemy/repository/memory/_async.py	66.66%	1 Missing and 2 partials ⚠️
advanced_alchemy/repository/memory/_sync.py	66.66%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #605      +/-   ##
==========================================
+ Coverage   79.69%   80.32%   +0.63%     
==========================================
  Files          87       87              
  Lines        6397     6405       +8     
  Branches      824      828       +4     
==========================================
+ Hits         5098     5145      +47     
+ Misses       1043     1000      -43     
- Partials      256      260       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
81.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/advanced-alchemy-docs-preview/605