Tracing.StartAsync without options (#1128)

Author: kblok

lib/PuppeteerSharp.Tests/TracingTests/TracingTests.cs

@@ -122,6 +122,15 @@ await Page.Tracing.StartAsync(new TracingOptions
             Assert.Equal(trace, buf);
         }
 
+        [Fact]
+        public async Task ShouldWorkWithoutOptions()
+        {
+            await Page.Tracing.StartAsync();
+            await Page.GoToAsync(TestConstants.ServerUrl + "/grid.html");
+            var trace = await Page.Tracing.StopAsync();
+            Assert.NotNull(trace);
+        }
+
         [Fact]
         public async Task ShouldSupportABufferWithoutAPath()
         {

lib/PuppeteerSharp/Tracing.cs

@@ -54,21 +54,21 @@ internal Tracing(CDPSession client)
         /// </summary>
         /// <returns>Start task</returns>
         /// <param name="options">Tracing options</param>
-        public Task StartAsync(TracingOptions options)
+        public Task StartAsync(TracingOptions options = null)
         {
             if (_recording)
             {
                 throw new InvalidOperationException("Cannot start recording trace while already recording trace.");
             }
 
-            var categories = options.Categories ?? _defaultCategories;
+            var categories = options?.Categories ?? _defaultCategories;
 
-            if (options.Screenshots)
+            if (options?.Screenshots == true)
             {
                 categories.Add("disabled-by-default-devtools.screenshot");
             }
 
-            _path = options.Path;
+            _path = options?.Path;
             _recording = true;
 
             return _client.SendAsync("Tracing.start", new TracingStartRequest