feat: improve finishTransaction logging and error handling

Author: hyochan

Sources/OpenIapModule.swift

@@ -290,43 +290,59 @@ public final class OpenIapModule: NSObject, OpenIapModuleProtocol {
     public func finishTransaction(purchase: PurchaseInput, isConsumable: Bool?) async throws -> Void {
         let identifier = purchase.id
 
+        OpenIapLog.debug("🔄 finishTransaction called with id: \(identifier)")
+
+        // First check pending transactions (most common case)
         if let pending = await state.getPending(id: identifier) {
+            OpenIapLog.debug("✅ Found pending transaction, finishing...")
             await pending.finish()
             await state.removePending(id: identifier)
+            OpenIapLog.debug("✅ Transaction finished successfully")
             return
         }
 
+        OpenIapLog.debug("⚠️ Transaction not in pending state, searching in StoreKit...")
+
+        // Try to parse as numeric ID for StoreKit lookup
         guard let numericId = UInt64(identifier) else {
-            let error = makePurchaseError(code: .purchaseError, message: "Invalid transaction identifier")
+            let error = makePurchaseError(code: .purchaseError, message: "Invalid transaction identifier: \(identifier) (not found in pending and not a valid numeric ID)")
+            OpenIapLog.error("❌ finishTransaction failed: \(error.message)")
             emitPurchaseError(error)
             throw error
         }
 
+        // Search in current entitlements
         for await result in Transaction.currentEntitlements {
             do {
                 let transaction = try checkVerified(result)
                 if transaction.id == numericId {
+                    OpenIapLog.debug("✅ Found in currentEntitlements, finishing...")
                     await transaction.finish()
+                    OpenIapLog.debug("✅ Transaction finished successfully")
                     return
                 }
             } catch {
                 continue
             }
         }
 
+        // Search in unfinished transactions
         for await result in Transaction.unfinished {
             do {
                 let transaction = try checkVerified(result)
                 if transaction.id == numericId {
+                    OpenIapLog.debug("✅ Found in unfinished, finishing...")
                     await transaction.finish()
+                    OpenIapLog.debug("✅ Transaction finished successfully")
                     return
                 }
             } catch {
                 continue
             }
         }
 
-        let error = makePurchaseError(code: .purchaseError, message: "Transaction not found")
+        let error = makePurchaseError(code: .purchaseError, message: "Transaction not found: \(identifier)")
+        OpenIapLog.error("❌ finishTransaction failed: \(error.message)")
         emitPurchaseError(error)
         throw error
     }