Improve errors (#237)

Author: DePasqualeOrg

Applications/StableDiffusionExample/ContentView.swift

@@ -105,8 +105,18 @@ actor ModelFactory {
         case loaded(ModelContainer<TextToImageGenerator>)
     }
 
-    enum SDError: Error {
+    enum SDError: LocalizedError {
         case unableToLoad
+
+        var errorDescription: String? {
+            switch self {
+            case .unableToLoad:
+                return String(
+                    localized:
+                        "Unable to load the Stable Diffusion model. Please check your internet connection or available storage space."
+                )
+            }
+        }
     }
 
     public nonisolated let configuration = StableDiffusionConfiguration.presetSDXLTurbo

Libraries/MLXLLM/Lora+Data.swift

@@ -2,8 +2,16 @@
 
 import Foundation
 
-enum LoRADataError: Error {
+enum LoRADataError: LocalizedError {
     case fileNotFound(URL, String)
+
+    var errorDescription: String? {
+        switch self {
+        case .fileNotFound(let directory, let name):
+            return String(
+                localized: "Could not find data file '\(name)' in directory '\(directory.path())'.")
+        }
+    }
 }
 
 /// Load a LoRA data file.

Libraries/MLXLMCommon/ModelFactory.swift

@@ -4,9 +4,16 @@ import Foundation
 import Hub
 import Tokenizers
 
-public enum ModelFactoryError: Error {
+public enum ModelFactoryError: LocalizedError {
     case unsupportedModelType(String)
     case unsupportedProcessorType(String)
+
+    public var errorDescription: String? {
+        switch self {
+        case .unsupportedModelType(let type): "Unsupported model type: \(type)"
+        case .unsupportedProcessorType(let type): "Unsupported processor type: \(type)"
+        }
+    }
 }
 
 /// Context of types that work together to provide a ``LanguageModel``.

Libraries/MLXLMCommon/UserInput.swift

@@ -175,10 +175,21 @@ public protocol UserInputProcessor {
     func prepare(input: UserInput) async throws -> LMInput
 }
 
-private enum UserInputError: Error {
+private enum UserInputError: LocalizedError {
     case notImplemented
     case unableToLoad(URL)
     case arrayError(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .notImplemented:
+            return String(localized: "This functionality is not implemented.")
+        case .unableToLoad(let url):
+            return String(localized: "Unable to load image from URL: \(url.path).")
+        case .arrayError(let message):
+            return String(localized: "Error processing image array: \(message).")
+        }
+    }
 }
 
 /// A do-nothing ``UserInputProcessor``.

Libraries/MLXVLM/VLMModelFactory.swift

@@ -6,12 +6,27 @@ import MLX
 import MLXLMCommon
 import Tokenizers
 
-public enum VLMError: Error {
+public enum VLMError: LocalizedError {
     case imageRequired
     case maskRequired
     case singleImageAllowed
     case imageProcessingFailure(String)
     case processing(String)
+
+    public var errorDescription: String? {
+        switch self {
+        case .imageRequired:
+            return String(localized: "An image is required for this operation.")
+        case .maskRequired:
+            return String(localized: "An image mask is required for this operation.")
+        case .singleImageAllowed:
+            return String(localized: "Only a single image is allowed for this operation.")
+        case .imageProcessingFailure(let details):
+            return String(localized: "Failed to process the image: \(details)")
+        case .processing(let details):
+            return String(localized: "Processing error: \(details)")
+        }
+    }
 }
 
 public struct BaseProcessorConfiguration: Codable, Sendable {

Libraries/StableDiffusion/Image.swift

@@ -7,9 +7,18 @@ import ImageIO
 import MLX
 import UniformTypeIdentifiers
 
-enum ImageError: Error {
+enum ImageError: LocalizedError {
     case failedToSave
     case unableToOpen
+
+    var errorDescription: String? {
+        switch self {
+        case .failedToSave:
+            return String(localized: "Failed to save the image to the specified location.")
+        case .unableToOpen:
+            return String(localized: "Unable to open the image file.")
+        }
+    }
 }
 
 /// Conversion utilities for moving between `MLXArray`, `CGImage` and files.

Libraries/StableDiffusion/StableDiffusion.swift

@@ -100,12 +100,26 @@ public protocol ImageToImageGenerator: ImageGenerator {
         -> DenoiseIterator
 }
 
-enum ModelContainerError: Error {
-    /// unable to create the particular type of model, e.g. it doesn't support image to image
+enum ModelContainerError: LocalizedError {
+    /// Unable to create the particular type of model, e.g. it doesn't support image to image
     case unableToCreate(String, String)
-
-    /// when operating in conserveMemory mode it tried to use a model that had been discarded
+    /// When operating in conserveMemory mode, it tried to use a model that had been discarded
     case modelDiscarded
+
+    var errorDescription: String? {
+        switch self {
+        case .unableToCreate(let modelId, let generatorType):
+            return String(
+                localized:
+                    "Unable to create a \(generatorType) with model ID '\(modelId)'. The model may not support this operation type."
+            )
+        case .modelDiscarded:
+            return String(
+                localized:
+                    "The model has been discarded to conserve memory and is no longer available. Please recreate the model container."
+            )
+        }
+    }
 }
 
 /// Container for models that guarantees single threaded access.