Improve error mapping

README.md

@@ -12,6 +12,5 @@ In order to use this package, you will first need to obtain an API key from [Sto
 - [x] Inline Documentation
 - [ ] README Documentation
 - [x] Access Control Audit
-- [ ] Error Handling
-- [ ] Swift 5 Async Support (?)
+- [x] Error Handling
 - [x] Add to SPI

Sources/StormGlass/Networking/SGNetworking.swift

@@ -64,7 +64,9 @@ public struct SGRequest<Endpoint: SGEndpoint> {
 
     public func fetch(completion: @escaping (Result<Endpoint.Response, Error>) -> Void) {
         do {
-            let task = try urlSession.dataTask(with: makeRequest()) { data, _, error in
+            let task = try urlSession.dataTask(with: makeRequest()) { data, response, error in
+                // Network Errors
+
                 if let error = error {
                     completion(.failure(error))
                     return
@@ -75,6 +77,22 @@ public struct SGRequest<Endpoint: SGEndpoint> {
                     return
                 }
 
+                // Error Handling
+
+                if let error = try? self.decoder.decode(SGErrorResponse.self, from: data) {
+                    completion(.failure(error))
+                    return
+                }
+
+                if let httpResponse = response as? HTTPURLResponse,
+                   let error = SGServiceError(statusCode: httpResponse.statusCode)
+                {
+                    completion(.failure(error))
+                    return
+                }
+
+                // Decode Response
+
                 do {
                     let result = try self.decoder.decode(Endpoint.Response.self, from: data)
                     completion(.success(result))

Sources/StormGlass/SGServiceError.swift

@@ -24,7 +24,7 @@ public enum SGServiceError: LocalizedError {
 
     internal init?(statusCode: Int) {
         switch statusCode {
-        case 400:
+        case 400, 422:
             self = .badRequest
         case 401:
             self = .unauthorised
@@ -71,3 +71,18 @@ public enum SGServiceError: LocalizedError {
         }
     }
 }
+
+public struct SGErrorResponse: Error, Decodable, CustomStringConvertible {
+    public struct Item: Decodable {
+        let key: String?
+        let params: [String]?
+    }
+
+    public let errors: Item
+
+    public var description: String {
+        errors.key ??
+            errors.params?.joined(separator: "\n\n") ??
+            "Unknown Error"
+    }
+}