[WIP] Fix error handling for string input data

[Copilot]

• Reproduce the runtime error and capture failing path
• Identify why Input data should be a string is emitted on this page only
• Implement the smallest safe fix in error handling
• Add or adjust focused tests for the fix (if existing test setup supports it)
• Run targeted validation and final security checks

Original prompt

This page works for a short time and then goes to the #file:error.tsx page containig the "derivedMessage" from the #file:Error.tsx component with the value "Input data should be a string". This only happens on this page and no other.

For a moment the correct page shows up, so i assume the SSR and first render works, but for some reason the server side error page shows

The user has attached the following file paths as relevant context:

• components\Error\Error.tsx
• app\error.tsx
• AGENTS.md

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