feat: Add invalid struct error

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### main
 [Full Changelog](https://github.com/parse-community/Parse-Swift/compare/1.9.4...main)
 * _Contributing to this repo? Add info about your change here to be included in the next release_
+-  Add more detail to invalid struct errors ([#238](https://github.com/parse-community/Parse-Swift/pull/211)), thanks to [Daniel Blyth](https://github.com/dblythy).
 
 ### 1.9.4
 [Full Changelog](https://github.com/parse-community/Parse-Swift/compare/1.9.3...1.9.4)

Sources/ParseSwift/API/URLSession+extensions.swift

@@ -66,6 +66,10 @@ extension URLSession {
                           let json = try? JSONSerialization
                             .data(withJSONObject: responseData,
                               options: .prettyPrinted) else {
+                        let err = (error as NSError)
+                        if err.code == 4865, let description = err.userInfo["NSDebugDescription"] {
+                            return .failure(ParseError(code: .invalidStruct, message: "Invalid struct: \(description)"))
+                        }
                         return .failure(ParseError(code: .unknownError,
                                                    // swiftlint:disable:next line_length
                                                    message: "Error decoding parse-server response: \(response) with error: \(error.localizedDescription) Format: \(String(describing: String(data: responseData, encoding: .utf8)))"))

Sources/ParseSwift/Types/CloudViewModel.swift

@@ -29,6 +29,7 @@ open class CloudViewModel<T: ParseCloud>: CloudObservable {
     }
 
     /// Updates and notifies when there is an error retrieving the results.
+    // swiftlint:disable:next redundant_optional_initialization
     open var error: ParseError? = nil {
         willSet {
             if newValue != nil {

Sources/ParseSwift/Types/ParseError.swift

@@ -352,6 +352,11 @@ public struct ParseError: ParseType, Decodable, Swift.Error {
          */
         case xDomainRequest = 602
 
+        /**
+         Error code indicating the Parse Swift struct is invalid.
+         */
+        case invalidStruct = 603
+
         /**
          Error code indicating any other custom error sent from the Parse Server.
          */

Sources/ParseSwift/Types/QueryViewModel.swift

@@ -38,6 +38,7 @@ open class QueryViewModel<T: ParseObject>: QueryObservable {
     }
 
     /// Updates and notifies when there is an error retrieving the results.
+    // swiftlint:disable:next redundant_optional_initialization
     open var error: ParseError? = nil {
         willSet {
             if newValue != nil {

Tests/ParseSwiftTests/ParseQueryTests.swift

@@ -723,6 +723,18 @@ class ParseQueryTests: XCTestCase { // swiftlint:disable:this type_body_length
         }
 
         let query = GameScore.query()
+        do {
+            _ = try query.first(options: [])
+            XCTFail("Should have thrown error")
+        } catch {
+            guard let error = error as? ParseError else {
+                XCTFail("Should have casted as ParseError")
+                return
+            }
+            // swiftlint:disable:next line_length
+            XCTAssertEqual(error.message, "Invalid struct: No value associated with key CodingKeys(stringValue: \"score\", intValue: nil) (\"score\").")
+            XCTAssertEqual(error.code, .invalidStruct)
+        }
         XCTAssertThrowsError(try query.first(options: []))
     }