Bits of .NET

🔗 Don’t Lose the Original Error

Throwing new Error() loses original stack. Error cause chains errors. See full context.

📝 Without Error Cause (Lost Context)

try {
  await fetchUser(userId);
} catch (err) {
  throw new Error(`Failed to get user ${userId}`);
  // Original error stack lost!
}

✅ With Error Cause (Full Context)

try {
  await fetchUser(userId);
} catch (err) {
  throw new Error(`Failed to get user ${userId}`, { cause: err });
  // Original error accessible via error.cause
}

// Multi-level chain
try {
  // Database error
} catch (dbError) {
  try {
    // Try fallback
  } catch (fallbackError) {
    throw new Error(`Both primary and fallback failed`, { 
      cause: { primary: dbError, fallback: fallbackError }
    });
  }
}

✅ Real-World Example

async function getOrderWithDetails(orderId) {
  try {
    const order = await fetchOrder(orderId);
    const user = await fetchUser(order.userId);
    const products = await fetchProducts(order.productIds);
    return { order, user, products };
  } catch (err) {
    // Add context at each level
    throw new Error(`Failed to load order ${orderId}`, { cause: err });
  }
}

// Later in error handler
try {
  await getOrderWithDetails(123);
} catch (err) {
  console.error(err.message);  // "Failed to load order 123"
  console.error(err.cause);     // Original fetch error
}

💡 Benefits

• Preserves original error stack trace
• Adds context without losing details
• Better debugging in production
• Logging services show full chain