fixes #57

Author: leastprivilege

src/IdentityModel.OidcClient/IdentityModel.OidcClient.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <VersionPrefix>2.5.0</VersionPrefix>
+    <VersionPrefix>2.5.1</VersionPrefix>
     <!--<VersionSuffix>preview3</VersionSuffix>-->
     <Authors>Dominick Baier;Brock Allen</Authors>
     <TargetFrameworks>net452;netstandard1.4;netstandard2.0</TargetFrameworks>

src/IdentityModel.OidcClient/OidcClient.cs

@@ -113,9 +113,10 @@ public async Task<LoginResult> LoginAsync(LoginRequest request)
         /// </summary>
         /// <param name="request">The logout request.</param>
         /// <returns></returns>
-        public string PrepareLogout(LogoutRequest request = null)
+        public async Task<string> PrepareLogoutAsync(LogoutRequest request = null)
         {
             if (request == null) request = new LogoutRequest();
+            await EnsureConfigurationAsync();
 
             var endpoint = _options.ProviderInformation.EndSessionEndpoint;
             if (endpoint.IsMissing())
@@ -134,6 +135,7 @@ public string PrepareLogout(LogoutRequest request = null)
         public async Task LogoutAsync(LogoutRequest request = null)
         {
             if (request == null) request = new LogoutRequest();
+            await EnsureConfigurationAsync();
 
             await _authorizeClient.EndSessionAsync(request);
         }