PR recommendations: added null checks where FindByX was added, using the same exception as ASP.NET Identity 2

src/Umbraco.Web/Editors/AuthenticationController.cs

@@ -131,6 +131,7 @@ namespace Umbraco.Web.Editors
         public async Task<HttpResponseMessage> PostUnLinkLogin(UnLinkLoginModel unlinkLoginModel)
         {
             var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());
+            if (user == null) throw new InvalidOperationException("Could not find user");
 
             var result = await UserManager.RemoveLoginAsync(
                 user,

src/Umbraco.Web/Editors/BackOfficeController.cs

@@ -329,6 +329,7 @@ namespace Umbraco.Web.Editors
             }
 
             var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());
+            if (user == null) throw new InvalidOperationException("Could not find user");
 
             var result = await UserManager.AddLoginAsync(user,
                 new UserLoginInfo(loginInfo.Login.LoginProvider, loginInfo.Login.ProviderKey, loginInfo.Login.LoginProvider));

src/Umbraco.Web/Editors/CurrentUserController.cs

@@ -159,6 +159,8 @@ namespace Umbraco.Web.Editors
         public async Task<UserDetail> PostSetInvitedUserPassword([FromBody]string newPassword)
         {
             var user = await UserManager.FindByIdAsync(Security.GetUserId().ResultOr(0).ToString());
+            if (user == null) throw new InvalidOperationException("Could not find user");
+
             var result = await UserManager.AddPasswordAsync(user, newPassword);
 
             if (result.Succeeded == false)

src/Umbraco.Web/Security/BackOfficeUserManager.cs

@@ -306,6 +306,8 @@ namespace Umbraco.Web.Security
         public async Task<IdentityResult> ChangePasswordWithResetAsync(int userId, string token, string newPassword)
         {
             var user = await base.FindByIdAsync(userId.ToString());
+            if (user == null) throw new InvalidOperationException("Could not find user");
+
             var result = await base.ResetPasswordAsync(user, token, newPassword);
             if (result.Succeeded) RaisePasswordChangedEvent(userId);
             return result;
@@ -317,24 +319,7 @@ namespace Umbraco.Web.Security
             if (result.Succeeded) RaisePasswordChangedEvent(user.Id);
             return result;
         }
-
-        /// <summary>
-        /// Override to determine how to hash the password
-        /// </summary>
-        /// <param name="store"></param>
-        /// <param name="user"></param>
-        /// <param name="password"></param>
-        /// <returns></returns>
-        protected override async Task<PasswordVerificationResult> VerifyPasswordAsync(IUserPasswordStore<T> store, T user, string password)
-        {
-            var userAwarePasswordHasher = PasswordHasher;
-            if (userAwarePasswordHasher == null)
-                return await base.VerifyPasswordAsync(store, user, password);
-
-            var hash = await store.GetPasswordHashAsync(user, CancellationToken.None);
-            return userAwarePasswordHasher.VerifyHashedPassword(user, hash, password);
-        }
-
+        
         /// <summary>
         /// Override to determine how to hash the password
         /// </summary>

src/Umbraco.Web/Security/IdentityFactoryMiddleware.cs

@@ -12,22 +12,14 @@ namespace Umbraco.Web.Security
         where TResult : class, IDisposable
         where TOptions : IdentityFactoryOptions<TResult>
     {
-        /// <summary>
-        ///     Constructor
-        /// </summary>
         /// <param name="next">The next middleware in the OWIN pipeline to invoke</param>
         /// <param name="options">Configuration options for the middleware</param>
         public IdentityFactoryMiddleware(OwinMiddleware next, TOptions options)
             : base(next)
         {
-            if (options == null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-            if (options.Provider == null)
-            {
-                throw new ArgumentNullException("options.Provider");
-            }
+            if (options == null) throw new ArgumentNullException(nameof(options));
+            if (options.Provider == null) throw new ArgumentException("options.Provider");
+
             Options = options;
         }
 
@@ -74,9 +66,6 @@ namespace Umbraco.Web.Security
 
     public class IdentityFactoryProvider<T> where T : class, IDisposable
     {
-        /// <summary>
-        ///     Constructor
-        /// </summary>
         public IdentityFactoryProvider()
         {
             OnDispose = (options, instance) => { };