Replace TryGetInstance to GetInstance

src/StructureMap.Microsoft.DependencyInjection/StructureMapServiceProvider.cs

@@ -19,14 +19,15 @@ public StructureMapServiceProvider(IContainer container)
 
         public object GetService(Type serviceType)
         {
-            if (serviceType.IsGenericEnumerable())
+            // TryGetInstance doesn't resolve instances of concrete types
+            try
             {
-                // Ideally we'd like to call TryGetInstance here as well,
-                // but StructureMap does't like it for some weird reason.
-                return GetRequiredService(serviceType);
+                return Container.GetInstance(serviceType);
+            }
+            catch (StructureMapConfigurationException)
+            {
+                return null;
             }
-
-            return Container.TryGetInstance(serviceType);
         }
 
         public object GetRequiredService(Type serviceType)

test/StructureMap.Microsoft.DependencyInjection.Tests/StructureMapServiceProviderTests.cs

@@ -24,6 +24,16 @@ public void can_start_and_tear_down_a_scope_from_the_provider()
             Assert.IsType<BlueWidget>(provider.GetRequiredService(typeof(IWidget)));
         }
 
+        [Fact]
+        public void get_service_without_registered_types_return_null()
+        {
+            var root = new Container();
+
+            var provider = new StructureMapServiceProvider(root);
+            Assert.Same(provider.Container, root);
+            Assert.Null(provider.GetService(typeof(IWidget)));
+        }
+
         public interface IWidget { }
 
         public class BlueWidget : IWidget { }