Handle thrown Keychain errors with informational alerts

Shared/Account/AccountModel.swift

@@ -6,6 +6,9 @@ enum AccountError: Error {
     case usernameNotFound
     case serverNotFound
     case invalidServerURL
+    case couldNotSaveTokenToKeychain
+    case couldNotFetchTokenFromKeychain
+    case couldNotDeleteTokenFromKeychain
 }
 
 extension AccountError: LocalizedError {
@@ -31,6 +34,21 @@ extension AccountError: LocalizedError {
                 "Please enter a valid instance domain name. It should look like \"https://example.com\" or \"write.as\".",  // swiftlint:disable:this line_length
                 comment: ""
             )
+        case .couldNotSaveTokenToKeychain:
+            return NSLocalizedString(
+                "There was a problem trying to save your access token to the device, please try logging in again.",
+                comment: ""
+            )
+        case .couldNotFetchTokenFromKeychain:
+            return NSLocalizedString(
+                "There was a problem trying to fetch your access token from the device, please try logging in again.",
+                comment: ""
+            )
+        case .couldNotDeleteTokenFromKeychain:
+            return NSLocalizedString(
+                "There was a problem trying to delete your access token from the device, please try logging out again.",
+                comment: ""
+            )
         }
     }
 }

Shared/Extensions/WriteFreelyModel+APIHandlers.swift

@@ -10,9 +10,16 @@ extension WriteFreelyModel {
             let user = try result.get()
             fetchUserCollections()
             fetchUserPosts()
-            saveTokenToKeychain(user.token, username: user.username, server: account.server)
+            do {
-            DispatchQueue.main.async {
+                try saveTokenToKeychain(user.token, username: user.username, server: account.server)
-                self.account.login(user)
+                DispatchQueue.main.async {
+                    self.account.login(user)
+                }
+            } catch {
+                DispatchQueue.main.async {
+                    self.loginErrorMessage = "There was a problem storing your access token to the Keychain."
+                    self.isPresentingLoginErrorAlert = true
+                }
             }
         } catch WFError.notFound {
             DispatchQueue.main.async {

Shared/Models/WriteFreelyModel.swift

@@ -51,18 +51,25 @@ final class WriteFreelyModel: ObservableObject {
                     print("Server URL not found")
                     return
                 }
-                guard let token = self.fetchTokenFromKeychain(
+                do {
-                        username: self.account.username,
+                    guard let token = try self.fetchTokenFromKeychain(
-                        server: self.account.server
+                            username: self.account.username,
-                ) else {
+                            server: self.account.server
-                    print("Could not fetch token from Keychain")
+                    ) else {
-                    return
+                        self.loginErrorMessage = AccountError.couldNotFetchTokenFromKeychain.localizedDescription
+                        self.isPresentingLoginErrorAlert = true
+                        return
+                    }
+
+                    self.account.login(WFUser(token: token, username: self.account.username))
+                    self.client = WFClient(for: serverURL)
+                    self.client?.user = self.account.user
+                    self.fetchUserCollections()
+                    self.fetchUserPosts()
+                } catch {
+                    self.loginErrorMessage = AccountError.couldNotFetchTokenFromKeychain.localizedDescription
+                    self.isPresentingLoginErrorAlert = true
                 }
-                self.account.login(WFUser(token: token, username: self.account.username))
-                self.client = WFClient(for: serverURL)
-                self.client?.user = self.account.user
-                self.fetchUserCollections()
-                self.fetchUserPosts()
             }
         }