🩹 Fix AttributeError validating bad DOAS user definition

[s-weigand]

During the review of #1510 we found an inherited bug from the DOAS megacomplex where a faulty user definition would raise an AttributeError when the ItemIssue get converted to a string that is show to users.

Change summary

• 🧪 Add failing test reproducing the AttributeError validating a bad DOAS user definition
• 🩹 Fix AttributeError validating bad DOAS user definition

Checklist

• [ ] ✔️ Passing the tests (mandatory for all PR's)
• [ ] 🚧 Added changes to changelog (mandatory for all PR's)

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.7%. Comparing base (2c88dce) to head (5e1c3b0). Report is 17 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1513 +/- ## ======================================= + Coverage 88.6% 88.7% +0.1% ======================================= Files 107 107 Lines 5128 5134 +6 Branches 962 965 +3 ======================================= + Hits 4544 4556 +12 + Misses 468 463 -5 + Partials 116 115 -1 ```

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[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarCloud