Null checks and property uses

src/Umbraco.Web/Install/InstallSteps/NewInstallStep.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Specialized;
 using System.Net.Http;
 using System.Text;
@@ -65,6 +65,9 @@ namespace Umbraco.Web.Install.InstallSteps
 
             //To change the password here we actually need to reset it since we don't have an old one to use to change
             var resetToken = await userManager.GeneratePasswordResetTokenAsync(membershipUser);
+            if (string.IsNullOrWhiteSpace(resetToken))
+                throw new InvalidOperationException("Could not reset password: unable to generate internal reset token");
+
             var resetResult = await userManager.ChangePasswordWithResetAsync(membershipUser.Id, resetToken, user.Password.Trim());
             if (!resetResult.Succeeded)
             {

src/Umbraco.Web/Security/AuthenticationManagerExtensions.cs

@@ -78,17 +78,14 @@ namespace Umbraco.Web.Security
         /// <returns></returns>
         public static async Task<ExternalLoginInfo> GetExternalLoginInfoAsync(this IAuthenticationManager manager, string authenticationType)
         {
-            if (manager == null)
-            {
-                throw new ArgumentNullException("manager");
-            }
+            if (manager == null) throw new ArgumentNullException(nameof(manager));
             return GetExternalLoginInfo(await manager.AuthenticateAsync(authenticationType));
         }
         
         public static IEnumerable<AuthenticationDescription> GetExternalAuthenticationTypes(this IAuthenticationManager manager)
         {
             if (manager == null) throw new ArgumentNullException(nameof(manager));
-            return manager.GetAuthenticationTypes(d => d.Properties != null && d.Properties.ContainsKey("Caption"));
+            return manager.GetAuthenticationTypes(d => d.Properties != null && d.Caption != null);
         }
 
         public static ClaimsIdentity CreateTwoFactorRememberBrowserIdentity(this IAuthenticationManager manager, string userId)