Merge pull request #73 from OmniSharp/nullref-fail

fix argument exception from newtonsoft.json

Author: david-driscoll

src/Server/Matchers/ResolveCommandMatcher.cs

@@ -29,7 +29,10 @@ public IEnumerable<ILspHandlerDescriptor> FindHandler(object parameters, IEnumer
         {
             if (parameters is ICanBeResolved canBeResolved)
             {
-                var handlerType = canBeResolved.Data?.Value<string>(PrivateHandlerTypeName);
+                string handlerType = null;
+                if (canBeResolved.Data != null)
+                    handlerType = canBeResolved.Data.Value<string>(PrivateHandlerTypeName);
+
                 if (string.IsNullOrWhiteSpace(handlerType))
                 {
                     foreach (var descriptor in descriptors)

test/Lsp.Tests/Matchers/ResolveCommandMatcherTests.cs

@@ -112,6 +112,33 @@ public void Should_Return_CodeLensResolve_Descriptor()
             result.Should().Contain(x => x.Handler == resolveHandler2);
         }
 
+        [Fact]
+        public void Should_Handle_Null_Data()
+        {
+            // Given
+            var handlerMatcher = new ResolveCommandMatcher(_logger);
+            var resolveHandler = Substitute.For<ICompletionResolveHandler>();
+            resolveHandler.CanResolve(Arg.Any<CompletionItem>()).Returns(true);
+
+            // When
+            var result = handlerMatcher.FindHandler(new CompletionItem() { },
+                    new List<HandlerDescriptor> {
+                        new HandlerDescriptor(DocumentNames.CompletionResolve,
+                            "Key",
+                            resolveHandler,
+                            resolveHandler.GetType(),
+                            typeof(CompletionItem),
+                            null,
+                            null,
+                            () => { }),
+                    })
+                .ToArray();
+
+            // Then
+            result.Should().NotBeNullOrEmpty();
+            result.Should().Contain(x => x.Handler == resolveHandler);
+        }
+
         [Fact]
         public void Should_Return_CompletionResolve_Descriptor()
         {