Preserve SerializableError in CachedError for proper error handling

[cjustice]

Preserve SerializableError in CachedError for proper error handling

Problem

When idempotent requests return cached errors, consumers receive CachedError instances but have no way to determine what the original exception type was. The SerializableError contains crucial type information (type: String with the fully qualified class name), but it was discarded when converting to CachedError.

This prevents consumers from properly mapping cached errors to appropriate error responses based on the exception type.

Current Behavior

// Before
SerializableError(
  type = "com.example.InsufficientBalanceException",
  message = "Insufficient balance"
)
  ↓
CachedError("[InsufficientBalanceException] Insufficient balance")
  // SerializableError is lost! ❌

Consumers receive the CachedError but cannot determine the original exception type programmatically.

Solution

Preserve the SerializableError as a field in CachedError so consumers can access the original exception type information and handle errors appropriately.

// After
SerializableError(
  type = "com.example.InsufficientBalanceException",
  message = "Insufficient balance"
)
  ↓
CachedError(
  message = "[InsufficientBalanceException] Insufficient balance",
  serializableError = SerializableError(...)  // ✅ Preserved!
)

Consumers can now access cachedError.serializableError.type to determine the original exception type.

Changes

common/src/main/kotlin/xyz/block/bittycity/common/idempotency/SerializableError.kt:

1. Added serializableError: SerializableError field to CachedError data class
2. Updated SerializableError.asCachedError() to pass this when constructing CachedError

data class CachedError(
  override val message: String?,
  val serializableError: SerializableError  // ← New field
) : Throwable(message)

fun SerializableError.asCachedError(): CachedError =
  CachedError("[$type] $message", this)  // ← Pass SerializableError

Impact

Breaking Change: Yes - CachedError constructor signature has changed.

Migration Path:

• Recommended: Use SerializableError.asCachedError() (already updated)
• If constructing directly: Add serializableError parameter to constructor calls

Benefits:

• Consumers can properly handle cached errors based on exception type
• No information loss during error serialization/caching
• Enables type-based error handling in idempotent request flows

Example Consumer Usage

when (error) {
  is CachedError -> {
    // Can now inspect the original exception type
    when (error.serializableError.type) {
      "com.example.InsufficientBalanceException" -> handleInsufficientBalance()
      "com.example.InvalidParameterException" -> handleInvalidParameter()
      else -> handleGenericError()
    }
  }
  // ... handle other error types
}