Denver feedback: Include error messages in the error code.

Author: aashishpatil-g

Sources/DataConnectError.swift

@@ -36,5 +36,5 @@ public enum DataConnectError: Error {
   case invalidTimestampFormat
 
   /// generic operation execution error
-  case operationExecutionFailed
+  case operationExecutionFailed(messages: String?)
 }

Sources/Internal/GrpcClient.swift

@@ -27,6 +27,7 @@ import SwiftProtobuf
 @available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *)
 typealias FirebaseDataConnectAsyncClient =
   Google_Firebase_Dataconnect_V1beta_ConnectorServiceAsyncClient
+typealias FirebaseDataConnectGraphqlError = Google_Firebase_Dataconnect_V1beta_GraphqlError
 
 @available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *)
 actor GrpcClient: CustomStringConvertible {
@@ -151,7 +152,8 @@ actor GrpcClient: CustomStringConvertible {
 
       // Not doing error decoding here
       guard results.errors.isEmpty else {
-        throw DataConnectError.operationExecutionFailed
+        throw DataConnectError
+          .operationExecutionFailed(messages: createErrorJson(errors: results.errors))
       }
 
       if let decodedResults = try codec.decode(result: results.data, asType: resultType) {
@@ -198,7 +200,8 @@ actor GrpcClient: CustomStringConvertible {
         .debug("executeMutation() receives response: \(resultsString, privacy: .private).")
 
       guard results.errors.isEmpty else {
-        throw DataConnectError.operationExecutionFailed
+        throw DataConnectError
+          .operationExecutionFailed(messages: createErrorJson(errors: results.errors))
       }
 
       if let decodedResults = try codec.decode(result: results.data, asType: resultType) {
@@ -216,6 +219,22 @@ actor GrpcClient: CustomStringConvertible {
     }
   }
 
+  private func createErrorJson(errors: [FirebaseDataConnectGraphqlError]) -> String? {
+    var errorMessages = [String]()
+    for err in errors {
+      errorMessages.append(err.message)
+    }
+
+    do {
+      let jsonEncoder = JSONEncoder()
+      let jsonData = try jsonEncoder.encode(errorMessages)
+      return String(data: jsonData, encoding: .utf8)
+    } catch {
+      DataConnectLogger.error("Error encoding partial error list")
+      return nil
+    }
+  }
+
   func createCallOptions() async -> CallOptions {
     var headers = HPACKHeaders()