fix(@Persist): prevent heap overflow in error handler

[apankov1]

Summary

The @Persist proxy error handler was auto-vivifying {} on ANY error during property access, causing:

1. Silent data corruption: Original property values replaced with empty objects
2. Heap overflow: Infinite proxy recursion when the getter continues to throw

Root Cause

// Before: creates {} and recurses infinitely
} catch (e) {
    console.error(`Error accessing property ${String(key)}:`, e);
    const newObj = {};
    Reflect.set(target, key, newObj);
    return createDeepProxy(newObj, instance, propertyKey, triggerPersist);
}

If a getter throws, the error handler:

1. Creates a new empty object
2. Sets it on the target (corrupting the original)
3. Returns a new proxy wrapping the empty object
4. The next access triggers the same getter → same error → infinite loop

Fix

} catch (e) {
    console.error(`Error accessing property ${String(key)}:`, e);
    // Return undefined on error - don't auto-vivify
    return undefined;
}

Test Plan

• Added test: throwing getter returns undefined, no heap overflow
• Added test: original object not corrupted on error

Related

• fix(@Persist): prevent null auto-vivification on read operations #93 - Separate fix for null auto-vivification in same code area

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Code in this PR was AI-assisted and exercised against a pet project that experienced the bug.