Fix crashes related to loading React 16.4.1

src/React.Core/JavaScriptEngineFactory.cs

@@ -135,7 +135,7 @@ protected virtual void InitialiseEngine(IJsEngine engine)
 			}
 
 			LoadUserScripts(engine);
-			if (!_config.LoadReact)
+			if (!_config.LoadReact && _scriptLoadException == null)
 			{
 				// We expect to user to have loaded their own version of React in the scripts that
 				// were loaded above, let's ensure that's the case. 

src/React.Core/Resources/shims.js

@@ -3,12 +3,12 @@
  *  All rights reserved.
  *
  *  This source code is licensed under the BSD-style license found in the
- *  LICENSE file in the root directory of this source tree. An additional grant 
+ *  LICENSE file in the root directory of this source tree. An additional grant
  *  of patent rights can be found in the PATENTS file in the same directory.
  */
 
 var global = global || {};
-var React, ReactDOM, ReactDOMServer;
+var React, ReactDOM, ReactDOMServer, setTimeout, clearTimeout;
 
 // Basic console shim. Caches all calls to console methods.
 function MockConsole() {
@@ -68,6 +68,20 @@ function ReactNET_initReact() {
 	return false;
 }
 
+setTimeout = setTimeout || global.setTimeout;
+if (setTimeout === undefined) {
+	setTimeout = function() {
+		throw new Error('setTimeout is not supported in server-rendered Javascript.');
+	}
+}
+
+clearTimeout = clearTimeout || global.clearTimeout;
+if (clearTimeout === undefined) {
+	clearTimeout = function() {
+		throw new Error('clearTimeout is not supported in server-rendered Javascript.');
+	}
+}
+
 /**
  * Polyfill for engines that do not support Object.assign
  */
@@ -94,4 +108,4 @@ if (typeof Object.assign !== 'function') {
 		}
 		return to;
 	};
-}
+}

tests/React.Tests/Core/JavaScriptEngineFactoryTest.cs

@@ -164,6 +164,28 @@ public void ShouldThrowIfReactVersionNotLoaded()
 			});
 		}
 
+		[Fact]
+		public void ShouldThrowScriptErrorIfReactFails()
+		{
+			var config = new Mock<IReactSiteConfiguration>();
+			config.Setup(x => x.ScriptsWithoutTransform).Returns(new List<string> {"foo.js"});
+			config.Setup(x => x.LoadReact).Returns(false);
+			var fileSystem = new Mock<IFileSystem>();
+			fileSystem.Setup(x => x.ReadAsString("foo.js")).Returns("FAIL PLZ");
+
+			var jsEngine = new Mock<IJsEngine>();
+			jsEngine.Setup(x => x.Evaluate<int>("1 + 1")).Returns(2);
+			jsEngine.Setup(x => x.Execute("FAIL PLZ")).Throws(new JsRuntimeException("Fail")
+			{
+				LineNumber = 42,
+				ColumnNumber = 911,
+			});
+			var factory = CreateFactory(config, fileSystem, () => jsEngine.Object);
+
+			var ex = Assert.Throws<ReactScriptLoadException>(() => factory.GetEngineForCurrentThread());
+			Assert.Equal("Error while loading \"foo.js\": Fail\r\nLine: 42\r\nColumn: 911", ex.Message);
+		}
+
 		[Fact]
 		public void ShouldCatchErrorsWhileLoadingScripts()
 		{