Fix return URL.

backend/src/Squidex/Areas/IdentityServer/Config/CreateAdminInitializer.cs

@@ -27,7 +27,6 @@ public sealed class CreateAdminInitializer : IInitializable
     public CreateAdminInitializer(IServiceProvider serviceProvider, IOptions<MyIdentityOptions> identityOptions)
     {
         this.serviceProvider = serviceProvider;
-
         this.identityOptions = identityOptions.Value;
     }
 

backend/src/Squidex/Areas/IdentityServer/Controllers/Account/AccountController.cs

@@ -184,7 +184,7 @@ public sealed class AccountController : IdentityServerController
         {
             var provider = externalProviders[0].AuthenticationScheme;
 
-            var challengeRedirectUrl = Url.Action(nameof(ExternalCallback));
+            var challengeRedirectUrl = Url.Action(nameof(ExternalCallback), new { returnUrl });
             var challengeProperties = SignInManager.ConfigureExternalAuthenticationProperties(provider, challengeRedirectUrl);
 
             // Redirect to the external authentication provider.