Pass along decode error information so that it can be diagnosed

Contributes to IOS-761

Author: whattherestimefor

Mastodon/Scene/Discovery/News/DiscoveryNewsViewModel.swift

@@ -58,7 +58,7 @@ extension DiscoveryNewsViewModel {
                 query: .init(offset: nil, limit: nil),
                 authenticationBox: authenticationBox
             )
-        } catch let error as Mastodon.API.Error where error.httpResponseStatus.code == 404 {
+        } catch let error as Mastodon.API.Error where error.httpResponseStatus?.code == 404 {
             isServerSupportEndpoint = false
         } catch {
             // do nothing

MastodonSDK/Sources/MastodonCore/Extension/MastodonSDK/Mastodon+Entity+Error.swift

@@ -12,7 +12,11 @@ extension Mastodon.API.Error: LocalizedError {
 
     public var errorDescription: String? {
         guard let mastodonError = mastodonError else {
-            return "HTTP \(httpResponseStatus.code)"
+            if let httpResponseStatus {
+                return "HTTP \(httpResponseStatus.code)"
+            } else {
+                return nil
+            }
         }
         switch mastodonError {
         case .generic(let error):
@@ -21,12 +25,18 @@ extension Mastodon.API.Error: LocalizedError {
             } else {
                 return error.error
             }
+        case .decodeError(let message):
+            return message
         }
     }
 
     public var failureReason: String? {
         guard let mastodonError = mastodonError else {
-            return httpResponseStatus.reasonPhrase
+            if let httpResponseStatus {
+                return httpResponseStatus.reasonPhrase
+            } else {
+                return nil
+            }
         }
         switch mastodonError {
         case .generic(let error):
@@ -35,6 +45,8 @@ extension Mastodon.API.Error: LocalizedError {
             } else {
                 return error.errorDescription
             }
+        case .decodeError(let message):
+            return message
         }
     }
 

MastodonSDK/Sources/MastodonCore/Service/API/APIService+APIError.swift

@@ -53,7 +53,7 @@ extension APIService.APIError: LocalizedError {
                 guard error.httpResponseStatus != .ok else {
                     return "Unknown Error"
                 }
-                return error.httpResponseStatus.reasonPhrase
+                return error.httpResponseStatus?.reasonPhrase
             }
 
             return responseError.errorDescription

MastodonSDK/Sources/MastodonSDK/API/Error/Mastodon+API+Error+MastodonAPIError.swift

@@ -10,6 +10,7 @@ import Foundation
 extension Mastodon.API.Error {
     public enum MastodonError: Swift.Error {
         case generic(error: Mastodon.Entity.Error)
+        case decodeError(message: String)
 
         init(error: Mastodon.Entity.Error) {
             self = .generic(error: error)
@@ -24,13 +25,17 @@ extension Mastodon.API.Error.MastodonError: LocalizedError {
         switch self {
         case .generic(let error):
             return error.error
+        case .decodeError(let message):
+            return message
         }
     }
 
     public var failureReason: String? {
         switch self {
         case .generic(let error):
             return error.errorDescription
+        case .decodeError(let message):
+            return message
         }
     }
 

MastodonSDK/Sources/MastodonSDK/API/Error/Mastodon+API+Error.swift

@@ -11,11 +11,11 @@ import enum NIOHTTP1.HTTPResponseStatus
 extension Mastodon.API {
     public struct Error: Swift.Error {
 
-        public var httpResponseStatus: HTTPResponseStatus
+        public var httpResponseStatus: HTTPResponseStatus?
         public var mastodonError: MastodonError?
 
         init(
-            httpResponseStatus: HTTPResponseStatus,
+            httpResponseStatus: HTTPResponseStatus?,
             mastodonError: Mastodon.API.Error.MastodonError?
         ) {
             self.httpResponseStatus = httpResponseStatus

MastodonSDK/Sources/MastodonSDK/API/Mastodon+API.swift

@@ -246,13 +246,14 @@ extension Mastodon.API {
         do {
             return try Mastodon.API.decoder.decode(type, from: data)
         } catch let decodeError {
+            let fullErrorDescription = "URL: \(String(describing: response.url))\nData: \(String(data: data, encoding: .utf8) ?? "-")\nError:\(decodeError)\n----\n"
             #if DEBUG
-            debugPrint("URL: \(String(describing: response.url))\nData: \(String(data: data, encoding: .utf8) ?? "-")\nError:\(decodeError)\n----\n")
+            debugPrint(fullErrorDescription)
             #endif
 
             guard let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode != 200 else {
                 assertionFailure()
-                throw decodeError
+                throw Mastodon.API.Error(httpResponseStatus: nil, mastodonError: .decodeError(message: fullErrorDescription))
             }
 
             let httpResponseStatus = HTTPResponseStatus(statusCode: httpURLResponse.statusCode)