Fix NullReferenceException in HttpChain when _handlerType is null

WolverineWebApiFSharp/Library.fs

@@ -6,5 +6,8 @@ open Wolverine.Http
 [<WolverinePost("/discovered-fsharp-unit")>]
 let myHandler() =
     task {
-       () 
-    }
+       ()
+    }
+
+[<WolverineGet("/fsharp/is-authenticated")>]
+let isAuthenticated () = true

src/Http/Wolverine.Http.Tests/end_to_end.cs

@@ -35,6 +35,32 @@ public async Task post_returning_fsharp_taskunit()
         });
     }
 
+    [Fact]
+    public async Task get_fsharp_bool_endpoint()
+    {
+        var body = await Scenario(x =>
+        {
+            x.Get.Url("/fsharp/is-authenticated");
+            x.StatusCodeShouldBeOk();
+        });
+
+        var result = body.ReadAsJson<bool>();
+        result.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task get_csharp_static_bool_endpoint()
+    {
+        var body = await Scenario(x =>
+        {
+            x.Get.Url("/simple/bool");
+            x.StatusCodeShouldBeOk();
+        });
+
+        var result = body.ReadAsJson<bool>();
+        result.ShouldBeTrue();
+    }
+
     [Fact]
     public async Task retrieve_json_data()
     {

src/Http/Wolverine.Http.Tests/endpoint_discovery_and_construction.cs

@@ -22,6 +22,20 @@ public void discover_endpoint_returning_fsharp_taskunit()
         chain.ShouldNotBeNull();
     }
 
+    [Fact]
+    public void discover_fsharp_bool_endpoint()
+    {
+        var chain = HttpChains.ChainFor("GET", "/fsharp/is-authenticated");
+        chain.ShouldNotBeNull();
+    }
+
+    [Fact]
+    public void discover_csharp_static_bool_endpoint()
+    {
+        var chain = HttpChains.ChainFor("GET", "/simple/bool");
+        chain.ShouldNotBeNull();
+    }
+
     [Fact]
     public void read_order_from_attribute()
     {

src/Http/Wolverine.Http/HttpChain.Codegen.cs

@@ -84,15 +84,11 @@ bool ICodeFile.AttachTypesSynchronously(GenerationRules rules, Assembly assembly
         string containingNamespace)
     {
         Debug.WriteLine(_generatedType?.SourceCode);
-
-        _handlerType = assembly.ExportedTypes.FirstOrDefault(x => x.Name == _fileName);
 
-        if (_handlerType == null)
-        {
-            return false;
-        }
+        _handlerType = assembly.ExportedTypes.FirstOrDefault(x => x.Name == _fileName)
+            ?? assembly.GetTypes().FirstOrDefault(x => x.Name == _fileName);
 
-        return true;
+        return _handlerType != null;
     }
 
     string ICodeFile.FileName => _fileName!;

src/Http/Wolverine.Http/HttpChain.EndpointBuilder.cs

@@ -46,43 +46,42 @@ private bool tryApplyAsEndpointMetadataProvider(Type? type, RouteEndpointBuilder
         return false;
     }
 
+    private HttpHandler buildHandler()
+    {
+        this.InitializeSynchronously(_parent.Rules, _parent, _parent.Container.Services);
+
+        if (_handlerType == null)
+        {
+            throw new InvalidOperationException(
+                $"Failed to resolve the generated handler type for endpoint {_fileName} " +
+                $"({string.Join(", ", _httpMethods)} {RoutePattern?.RawText}) " +
+                $"on handler type {Method.HandlerType.FullNameInCode()}. " +
+                $"The generated source code was:\n{_generatedType?.SourceCode}");
+        }
+
+        return (HttpHandler)_parent.Container.QuickBuild(_handlerType);
+    }
+
     public RouteEndpoint BuildEndpoint(RouteWarmup warmup)
     {
         if (Endpoint != null) return Endpoint;
-        
+
         RequestDelegate? requestDelegate = null;
         if (_parent.Rules.TypeLoadMode == TypeLoadMode.Static && !DynamicCodeBuilder.WithinCodegenCommand)
         {
-            this.InitializeSynchronously(_parent.Rules, _parent, _parent.Container.Services);
-            var handler = (HttpHandler)_parent.Container.QuickBuild(_handlerType);
+            var handler = buildHandler();
             requestDelegate = handler.Handle;
         }
         else
         {
             if (warmup == RouteWarmup.Eager && !DynamicCodeBuilder.WithinCodegenCommand)
             {
-                this.InitializeSynchronously(_parent.Rules, _parent, _parent.Container.Services);
-                var handler = (HttpHandler)_parent.Container.QuickBuild(_handlerType);
+                var handler = buildHandler();
                 requestDelegate = c => handler.Handle(c);
             }
             else
             {
-                var handler = new Lazy<HttpHandler>(() =>
-                {
-                    this.InitializeSynchronously(_parent.Rules, _parent, _parent.Container.Services);
-
-                    try
-                    {
-                        return (HttpHandler)_parent.Container.QuickBuild(_handlerType);
-                    }
-                    catch (Exception e)
-                    {
-                        throw new InvalidOperationException(
-                            "Wolverine may be having trouble with concurrent access to the same route at startup. Set the WolverineHttpOptions.Warmup = Eager to work around this problem",
-                            e);
-                    }
-                });
-
+                var handler = new Lazy<HttpHandler>(buildHandler);
                 requestDelegate = c => handler.Value.Handle(c);
             }
         }

src/Http/WolverineWebApi/FakeEndpoint.cs

@@ -76,4 +76,10 @@ public string ReadEnumArgument(Direction direction)
     }
 }
 
+public static class NoDependencyEndpoints
+{
+    [WolverineGet("/simple/bool")]
+    public static bool GetBool() => true;
+}
+
 public class BigResponse;