🧪 Add minitest for erb.rb malformed data error handling

[hahwul]

🎯 What: The testing gap addressed: Missing error test for the second data processing block in erb.rb.
📊 Coverage: What scenarios are now tested: Injecting malformed weapon data (tags: 123 instead of an array) to trigger and assert the rescue => e error handling when processing tags and language categorizations.
✨ Result: The improvement in test coverage: We have an automated minitest suite test_erb.rb that simulates execution in a safe temp directory to confirm robustness without mutating the git tree.

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PR created automatically by Jules for task 1008594445152255818 started by @hahwul

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