Add descriptions to some error cases so they include some context of where they were thrown

roanutil · roanutil · commit 2a8e63287bbb · 2026-02-24T08:47:06.000-06:00
feature/identified-description
diff --git a/Sources/CoreDataRepository/CoreDataError.swift b/Sources/CoreDataRepository/CoreDataError.swift
@@ -21,15 +21,15 @@ public enum CoreDataError: Error, Hashable, Sendable {
     /// against the correct property.
     /// If the `NSAttributeDescription` is not for the correct or expected `NSEntityDescription`, this error is
     /// returned.
-    case propertyDoesNotMatchEntity
+    case propertyDoesNotMatchEntity(description: String?)
 
     /// CoreData may return a value of a related type to what is actually needed. If casting the value CoreData returns
     /// to the required type fails, this error is returned.
-    case fetchedObjectFailedToCastToExpectedType
+    case fetchedObjectFailedToCastToExpectedType(description: String?)
 
     /// It's possible for a persisted object to be flagged as deleted but still be fetched. If that happens, this error
     /// is returned.
-    case fetchedObjectIsFlaggedAsDeleted
+    case fetchedObjectIsFlaggedAsDeleted(description: String)
 
     /// If CoreData throws a `CocoaError`, it is embedded here.
     case cocoa(CocoaError)
@@ -48,13 +48,13 @@ public enum CoreDataError: Error, Hashable, Sendable {
     /// If a ``ManagedIdUrlReferencable`` value is used in a transaction where it is expected to already be persisted
     /// but has no `URL`
     /// representing the ``NSManagedObjectID``, this error is returned.
-    case noUrlOnItemToMapToObjectId
+    case noUrlOnItemToMapToObjectId(description: String)
 
     /// If a ``ManagedIdReferencable`` value is used in a transaction where it is expected to already be persisted but
     /// has no `NSManagedObjectID`, this error is returned.
-    case noObjectIdOnItem
+    case noObjectIdOnItem(description: String)
 
-    case noMatchFoundWhenReadingItem
+    case noMatchFoundWhenReadingItem(description: String)
 
     public var localizedDescription: String {
         switch self {
diff --git a/Sources/CoreDataRepository/CoreDataRepository+Aggregate.swift b/Sources/CoreDataRepository/CoreDataRepository+Aggregate.swift
@@ -411,7 +411,7 @@ extension CoreDataRepository {
     ) throws -> Value {
         let result = try context.fetch(request)
         guard let value: Value = result.asAggregateValue() else {
-            throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+            throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: nil)
         }
         return value
     }
@@ -426,7 +426,18 @@ extension CoreDataRepository {
         groupBy: NSAttributeDescription? = nil
     ) async -> Result<Value, CoreDataError> {
         guard entityDesc == attributeDesc.entity else {
-            return .failure(.propertyDoesNotMatchEntity)
+            guard let entityName = entityDesc.name ?? entityDesc.managedObjectClassName else {
+                return .failure(.propertyDoesNotMatchEntity(description: nil))
+            }
+            guard let attributeEntityName = attributeDesc.entity.name ?? attributeDesc.entity.managedObjectClassName
+            else {
+                return .failure(.propertyDoesNotMatchEntity(description: entityName))
+            }
+            return .failure(
+                .propertyDoesNotMatchEntity(
+                    description: "\(entityName) != \(attributeDesc.name).\(attributeEntityName)"
+                )
+            )
         }
         return await context.performInChild { scratchPad in
             let request = try NSFetchRequest<NSDictionary>.request(
diff --git a/Sources/CoreDataRepository/CoreDataRepository+BatchRequest.swift b/Sources/CoreDataRepository/CoreDataRepository+BatchRequest.swift
@@ -18,7 +18,7 @@ extension CoreDataRepository {
             context.transactionAuthor = transactionAuthor
             guard let result = try scratchPad.execute(request) as? NSBatchDeleteResult else {
                 context.transactionAuthor = nil
-                throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+                throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: request.description)
             }
             context.transactionAuthor = nil
             return result
@@ -36,7 +36,7 @@ extension CoreDataRepository {
             context.transactionAuthor = transactionAuthor
             guard let result = try scratchPad.execute(request) as? NSBatchInsertResult else {
                 context.transactionAuthor = nil
-                throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+                throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: request.description)
             }
             context.transactionAuthor = nil
             return result
@@ -54,7 +54,7 @@ extension CoreDataRepository {
             context.transactionAuthor = transactionAuthor
             guard let result = try scratchPad.execute(request) as? NSBatchUpdateResult else {
                 context.transactionAuthor = nil
-                throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+                throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: request.description)
             }
             context.transactionAuthor = nil
             return result
diff --git a/Sources/CoreDataRepository/CoreDataRepository+Delete.swift b/Sources/CoreDataRepository/CoreDataRepository+Delete.swift
@@ -70,7 +70,7 @@ extension CoreDataRepository {
             scratchPad.transactionAuthor = transactionAuthor
             let object = try item.readManaged(from: scratchPad)
             guard !object.isDeleted else {
-                throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+                throw CoreDataError.fetchedObjectIsFlaggedAsDeleted(description: item.errorDescription)
             }
             object.prepareForDeletion()
             scratchPad.delete(object)
diff --git a/Sources/CoreDataRepository/CoreDataRepository+Delete_Batch.swift b/Sources/CoreDataRepository/CoreDataRepository+Delete_Batch.swift
@@ -138,7 +138,8 @@ extension CoreDataRepository {
             for item in items {
                 let object = try item.readManaged(from: scratchPad)
                 guard !object.isDeleted else {
-                    throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+                    throw CoreDataError
+                        .fetchedObjectIsFlaggedAsDeleted(description: item.errorDescription)
                 }
                 object.prepareForDeletion()
                 scratchPad.delete(object)
diff --git a/Sources/CoreDataRepository/CoreDataRepository+Read_Batch.swift b/Sources/CoreDataRepository/CoreDataRepository+Read_Batch.swift
@@ -103,7 +103,8 @@ extension CoreDataRepository {
             try ids.map { id in
                 let managed = try Model.readManaged(id: id, from: readContext)
                 guard !managed.isDeleted else {
-                    throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+                    throw CoreDataError
+                        .fetchedObjectIsFlaggedAsDeleted(description: Model.errorDescription(for: id))
                 }
                 return try Model(managed: managed)
             }
@@ -122,7 +123,8 @@ extension CoreDataRepository {
             try items.map { item in
                 let managed = try item.readManaged(from: readContext)
                 guard !managed.isDeleted else {
-                    throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+                    throw CoreDataError
+                        .fetchedObjectIsFlaggedAsDeleted(description: item.errorDescription)
                 }
                 return try Model(managed: managed)
             }
@@ -142,7 +144,7 @@ extension CoreDataRepository {
             try managedIds.map { managedId in
                 let _managed = try readContext.notDeletedObject(for: managedId)
                 guard let managed = _managed as? Model.ManagedModel else {
-                    throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+                    throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: "\(Model.self)")
                 }
                 return try Model(managed: managed)
             }
@@ -163,7 +165,7 @@ extension CoreDataRepository {
                 let managedId = try readContext.objectId(from: managedIdUrl).get()
                 let _managed = try readContext.notDeletedObject(for: managedId)
                 guard let managed = _managed as? Model.ManagedModel else {
-                    throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+                    throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: "\(Model.self)")
                 }
                 return try Model(managed: managed)
             }
diff --git a/Sources/CoreDataRepository/FetchableUnmanagedModel.swift b/Sources/CoreDataRepository/FetchableUnmanagedModel.swift
@@ -67,6 +67,9 @@ public protocol FetchableUnmanagedModel: Sendable {
 
     /// ``NSFetchRequest`` for ``ManagedModel`` with a strongly typed ``NSFetchRequest.ResultType``
     static func managedFetchRequest() -> NSFetchRequest<ManagedModel>
+
+    /// A description of the context from where an error is thrown
+    var errorDescription: String { get }
 }
 
 extension FetchableUnmanagedModel {
@@ -77,4 +80,9 @@ extension FetchableUnmanagedModel {
                 .managedObjectClassName
         )
     }
+
+    @inlinable
+    public var errorDescription: String {
+        "\(Self.self)"
+    }
 }
diff --git a/Sources/CoreDataRepository/IdentifiedUnmanagedModel.swift b/Sources/CoreDataRepository/IdentifiedUnmanagedModel.swift
@@ -10,6 +10,8 @@ public protocol IdentifiedUnmanagedModel: ReadableUnmanagedModel {
     associatedtype UnmanagedId: Equatable
     var unmanagedId: UnmanagedId { get }
     static var unmanagedIdExpression: NSExpression { get }
+    /// Enables including ``UnmanagedId`` in ``errorDescription``
+    static func errorDescription(for unmanagedId: UnmanagedId) -> String
 }
 
 extension IdentifiedUnmanagedModel {
@@ -29,10 +31,12 @@ extension IdentifiedUnmanagedModel {
         )
         let fetchResult = try context.fetch(request)
         guard let managed = fetchResult.first, fetchResult.count == 1 else {
-            throw CoreDataError.noMatchFoundWhenReadingItem
+            throw CoreDataError
+                .noMatchFoundWhenReadingItem(description: "\(Self.self) -- id: \(errorDescription(for: id))")
         }
         guard !managed.isDeleted else {
-            throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+            throw CoreDataError
+                .fetchedObjectIsFlaggedAsDeleted(description: "\(Self.self) -- id: \(errorDescription(for: id))")
         }
         return managed
     }
diff --git a/Sources/CoreDataRepository/Internal/AggregateSubscription.swift b/Sources/CoreDataRepository/Internal/AggregateSubscription.swift
@@ -32,7 +32,7 @@ final class AggregateSubscription<Value: Numeric & Sendable>: Subscription<Value
             }
 
             guard let value: Value = result.asAggregateValue() else {
-                self?.fail(.fetchedObjectFailedToCastToExpectedType)
+                self?.fail(.fetchedObjectFailedToCastToExpectedType(description: nil))
                 return
             }
             self?.send(value)
@@ -93,7 +93,20 @@ final class AggregateSubscription<Value: Numeric & Sendable>: Subscription<Value
                 context: context,
                 continuation: continuation
             )
-            fail(.propertyDoesNotMatchEntity)
+            guard let entityName = entityDesc.name ?? entityDesc.managedObjectClassName else {
+                fail(.propertyDoesNotMatchEntity(description: nil))
+                return
+            }
+            guard let attributeEntityName = attributeDesc.entity.name ?? attributeDesc.entity.managedObjectClassName
+            else {
+                fail(.propertyDoesNotMatchEntity(description: entityName))
+                return
+            }
+            fail(
+                .propertyDoesNotMatchEntity(
+                    description: "\(entityName) != \(attributeDesc.name).\(attributeEntityName)"
+                )
+            )
             return
         }
         self.init(request: request, context: context, continuation: continuation)
diff --git a/Sources/CoreDataRepository/Internal/AggregateThrowingSubscription.swift b/Sources/CoreDataRepository/Internal/AggregateThrowingSubscription.swift
@@ -36,7 +36,7 @@ final class AggregateThrowingSubscription<Value: Numeric & Sendable>: ThrowingSu
             }
 
             guard let value: Value = result.asAggregateValue() else {
-                self?.fail(.fetchedObjectFailedToCastToExpectedType)
+                self?.fail(.fetchedObjectFailedToCastToExpectedType(description: nil))
                 return
             }
             self?.send(value)
@@ -97,7 +97,20 @@ final class AggregateThrowingSubscription<Value: Numeric & Sendable>: ThrowingSu
                 context: context,
                 continuation: continuation
             )
-            fail(.propertyDoesNotMatchEntity)
+            guard let entityName = entityDesc.name ?? entityDesc.managedObjectClassName else {
+                fail(.propertyDoesNotMatchEntity(description: nil))
+                return
+            }
+            guard let attributeEntityName = attributeDesc.entity.name ?? attributeDesc.entity.managedObjectClassName
+            else {
+                fail(.propertyDoesNotMatchEntity(description: entityName))
+                return
+            }
+            fail(
+                .propertyDoesNotMatchEntity(
+                    description: "\(entityName) != \(attributeDesc.name).\(attributeEntityName)"
+                )
+            )
             return
         }
         self.init(request: request, context: context, continuation: continuation)
diff --git a/Sources/CoreDataRepository/NSManagedObject+Helpers.swift b/Sources/CoreDataRepository/NSManagedObject+Helpers.swift
@@ -12,7 +12,7 @@ extension NSManagedObject {
     @inlinable
     public func asManagedModel<T: NSManagedObject>() throws -> T {
         guard let repoManaged = self as? T else {
-            throw CoreDataError.fetchedObjectFailedToCastToExpectedType
+            throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: "\(Self.self) -> \(T.self)")
         }
         return repoManaged
     }
diff --git a/Sources/CoreDataRepository/NSManagedObjectContext+Helpers.swift b/Sources/CoreDataRepository/NSManagedObjectContext+Helpers.swift
@@ -22,7 +22,7 @@ extension NSManagedObjectContext {
     public func notDeletedObject(for id: NSManagedObjectID) throws -> NSManagedObject {
         let object: NSManagedObject = try existingObject(with: id)
         guard !object.isDeleted else {
-            throw CoreDataError.fetchedObjectIsFlaggedAsDeleted
+            throw CoreDataError.fetchedObjectIsFlaggedAsDeleted(description: id.description)
         }
         return object
     }
diff --git a/Sources/CoreDataRepository/ReadableUnmanagedModel.swift b/Sources/CoreDataRepository/ReadableUnmanagedModel.swift
@@ -80,7 +80,7 @@ extension ReadableUnmanagedModel where Self: ManagedIdReferencable {
     @inlinable
     public func readManaged(from context: NSManagedObjectContext) throws -> ManagedModel {
         guard let managedId else {
-            throw CoreDataError.noObjectIdOnItem
+            throw CoreDataError.noObjectIdOnItem(description: "\(Self.self)")
         }
         return try context.notDeletedObject(for: managedId).asManagedModel()
     }
@@ -90,7 +90,7 @@ extension ReadableUnmanagedModel where Self: ManagedIdUrlReferencable {
     @inlinable
     public func readManaged(from context: NSManagedObjectContext) throws -> ManagedModel {
         guard let managedIdUrl else {
-            throw CoreDataError.noUrlOnItemToMapToObjectId
+            throw CoreDataError.noUrlOnItemToMapToObjectId(description: "\(Self.self)")
         }
         let managedId = try context.objectId(from: managedIdUrl).get()
         return try context.notDeletedObject(for: managedId).asManagedModel()
diff --git a/Sources/Internal/ModelsWithIntId/IdentifiableModel_Int.swift b/Sources/Internal/ModelsWithIntId/IdentifiableModel_Int.swift
@@ -105,6 +105,10 @@ extension IdentifiableModel_IntId: IdentifiedUnmanagedModel {
     }
 
     package nonisolated(unsafe) static let unmanagedIdExpression = NSExpression(forKeyPath: \ManagedModel_IntId.id)
+
+    package static func errorDescription(for unmanagedId: Int) -> String {
+        unmanagedId.description
+    }
 }
 
 extension IdentifiableModel_IntId: WritableUnmanagedModel {
diff --git a/Sources/Internal/ModelsWithUuidId/IdentifiableModel_Uuid.swift b/Sources/Internal/ModelsWithUuidId/IdentifiableModel_Uuid.swift
@@ -105,6 +105,10 @@ extension IdentifiableModel_UuidId: IdentifiedUnmanagedModel {
     }
 
     package nonisolated(unsafe) static let unmanagedIdExpression = NSExpression(forKeyPath: \ManagedModel_UuidId.id)
+
+    package static func errorDescription(for unmanagedId: UUID) -> String {
+        unmanagedId.uuidString
+    }
 }
 
 extension IdentifiableModel_UuidId: WritableUnmanagedModel {
diff --git a/Tests/CoreDataRepositoryTests/DeleteTests.swift b/Tests/CoreDataRepositoryTests/DeleteTests.swift
@@ -46,7 +46,11 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noMatchFoundWhenReadingItem):
+            case .failure(
+                .noMatchFoundWhenReadingItem(
+                    description: "\(modelType) -- id: \(modelType.seeded(1).unmanagedId.uuidString)"
+                )
+            ):
                 return
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
@@ -116,7 +120,7 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noObjectIdOnItem):
+            case .failure(.noObjectIdOnItem(description: "\(modelType)")):
                 return
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
@@ -237,7 +241,7 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noUrlOnItemToMapToObjectId):
+            case .failure(.noUrlOnItemToMapToObjectId(description: "\(modelType)")):
                 return
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
diff --git a/Tests/CoreDataRepositoryTests/Delete_BatchTests.swift b/Tests/CoreDataRepositoryTests/Delete_BatchTests.swift
@@ -548,7 +548,11 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noMatchFoundWhenReadingItem):
+            case .failure(
+                .noMatchFoundWhenReadingItem(
+                    description: "\(modelType) -- id: \(modelType.seeded(1).unmanagedId.uuidString)"
+                )
+            ):
                 break
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
@@ -671,7 +675,7 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noObjectIdOnItem):
+            case .failure(.noObjectIdOnItem(description: "\(modelType)")):
                 break
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
@@ -892,7 +896,7 @@ extension CoreDataRepositoryTests {
             switch result {
             case .success:
                 Issue.record("Not expecting success")
-            case .failure(.noUrlOnItemToMapToObjectId):
+            case .failure(.noUrlOnItemToMapToObjectId(description: "\(modelType)")):
                 break
             case let .failure(error):
                 Issue.record("Unexpected error: \(error)")
diff --git a/Tests/CoreDataRepositoryTests/ReadTests.swift b/Tests/CoreDataRepositoryTests/ReadTests.swift
diff --git a/Tests/CoreDataRepositoryTests/Read_BatchTests.swift b/Tests/CoreDataRepositoryTests/Read_BatchTests.swift
diff --git a/Tests/CoreDataRepositoryTests/UpdateTests.swift b/Tests/CoreDataRepositoryTests/UpdateTests.swift
diff --git a/Tests/CoreDataRepositoryTests/Update_BatchTests.swift b/Tests/CoreDataRepositoryTests/Update_BatchTests.swift

Original file line number	Diff line number	Diff line change
`@@ -70,7 +70,7 @@ extension CoreDataRepository {`
`70`	`70`	`scratchPad.transactionAuthor = transactionAuthor`
`71`	`71`	`let object = try item.readManaged(from: scratchPad)`
`72`	`72`	`guard !object.isDeleted else {`
`73`		`- throw CoreDataError.fetchedObjectIsFlaggedAsDeleted`
	`73`	`+ throw CoreDataError.fetchedObjectIsFlaggedAsDeleted(description: item.errorDescription)`
`74`	`74`	`}`
`75`	`75`	`object.prepareForDeletion()`
`76`	`76`	`scratchPad.delete(object)`
Original file line number	Diff line number	Diff line change
`@@ -103,7 +103,8 @@ extension CoreDataRepository {`
`103`	`103`	`try ids.map { id in`
`104`	`104`	`let managed = try Model.readManaged(id: id, from: readContext)`
`105`	`105`	`guard !managed.isDeleted else {`
`106`		`- throw CoreDataError.fetchedObjectIsFlaggedAsDeleted`
	`106`	`+ throw CoreDataError`
	`107`	`+ .fetchedObjectIsFlaggedAsDeleted(description: Model.errorDescription(for: id))`
`107`	`108`	`}`
`108`	`109`	`return try Model(managed: managed)`
`109`	`110`	`}`
`@@ -122,7 +123,8 @@ extension CoreDataRepository {`
`122`	`123`	`try items.map { item in`
`123`	`124`	`let managed = try item.readManaged(from: readContext)`
`124`	`125`	`guard !managed.isDeleted else {`
`125`		`- throw CoreDataError.fetchedObjectIsFlaggedAsDeleted`
	`126`	`+ throw CoreDataError`
	`127`	`+ .fetchedObjectIsFlaggedAsDeleted(description: item.errorDescription)`
`126`	`128`	`}`
`127`	`129`	`return try Model(managed: managed)`
`128`	`130`	`}`
`@@ -142,7 +144,7 @@ extension CoreDataRepository {`
`142`	`144`	`try managedIds.map { managedId in`
`143`	`145`	`let _managed = try readContext.notDeletedObject(for: managedId)`
`144`	`146`	`guard let managed = _managed as? Model.ManagedModel else {`
`145`		`- throw CoreDataError.fetchedObjectFailedToCastToExpectedType`
	`147`	`+ throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: "\(Model.self)")`
`146`	`148`	`}`
`147`	`149`	`return try Model(managed: managed)`
`148`	`150`	`}`
`@@ -163,7 +165,7 @@ extension CoreDataRepository {`
`163`	`165`	`let managedId = try readContext.objectId(from: managedIdUrl).get()`
`164`	`166`	`let _managed = try readContext.notDeletedObject(for: managedId)`
`165`	`167`	`guard let managed = _managed as? Model.ManagedModel else {`
`166`		`- throw CoreDataError.fetchedObjectFailedToCastToExpectedType`
	`168`	`+ throw CoreDataError.fetchedObjectFailedToCastToExpectedType(description: "\(Model.self)")`
`167`	`169`	`}`
`168`	`170`	`return try Model(managed: managed)`
`169`	`171`	`}`
Original file line number	Diff line number	Diff line change
`@@ -67,6 +67,9 @@ public protocol FetchableUnmanagedModel: Sendable {`
`67`	`67`
`68`	`68`	/// ``NSFetchRequest`` for ``ManagedModel`` with a strongly typed ``NSFetchRequest.ResultType``
`69`	`69`	`static func managedFetchRequest() -> NSFetchRequest<ManagedModel>`
	`70`	`+`
	`71`	`+ /// A description of the context from where an error is thrown`
	`72`	`+ var errorDescription: String { get }`
`70`	`73`	`}`
`71`	`74`
`72`	`75`	`extension FetchableUnmanagedModel {`
`@@ -77,4 +80,9 @@ extension FetchableUnmanagedModel {`
`77`	`80`	`.managedObjectClassName`
`78`	`81`	`)`
`79`	`82`	`}`
	`83`	`+`
	`84`	`+ @inlinable`
	`85`	`+ public var errorDescription: String {`
	`86`	`+ "\(Self.self)"`
	`87`	`+ }`
`80`	`88`	`}`
Original file line number	Diff line number	Diff line change
`@@ -10,6 +10,8 @@ public protocol IdentifiedUnmanagedModel: ReadableUnmanagedModel {`
`10`	`10`	`associatedtype UnmanagedId: Equatable`
`11`	`11`	`var unmanagedId: UnmanagedId { get }`
`12`	`12`	`static var unmanagedIdExpression: NSExpression { get }`
	`13`	+ /// Enables including ``UnmanagedId`` in ``errorDescription``
	`14`	`+ static func errorDescription(for unmanagedId: UnmanagedId) -> String`
`13`	`15`	`}`
`14`	`16`
`15`	`17`	`extension IdentifiedUnmanagedModel {`
`@@ -29,10 +31,12 @@ extension IdentifiedUnmanagedModel {`
`29`	`31`	`)`
`30`	`32`	`let fetchResult = try context.fetch(request)`
`31`	`33`	`guard let managed = fetchResult.first, fetchResult.count == 1 else {`
`32`		`- throw CoreDataError.noMatchFoundWhenReadingItem`
	`34`	`+ throw CoreDataError`
	`35`	`+ .noMatchFoundWhenReadingItem(description: "\(Self.self) -- id: \(errorDescription(for: id))")`
`33`	`36`	`}`
`34`	`37`	`guard !managed.isDeleted else {`
`35`		`- throw CoreDataError.fetchedObjectIsFlaggedAsDeleted`
	`38`	`+ throw CoreDataError`
	`39`	`+ .fetchedObjectIsFlaggedAsDeleted(description: "\(Self.self) -- id: \(errorDescription(for: id))")`
`36`	`40`	`}`
`37`	`41`	`return managed`
`38`	`42`	`}`