[release/7.0-rc1] [wasm] Unwrap exception when calling entrypoint (#74263)

* Unwrap exception,

* WBT.

Co-authored-by: Marek Fišera <[email protected]>

Author: github-actions[bot]

src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Interop/JavaScriptExports.cs

@@ -85,6 +85,9 @@ public static void CallEntrypoint(JSMarshalerArgument* arguments_buffer)
             }
             catch (Exception ex)
             {
+                if (ex is TargetInvocationException refEx && refEx.InnerException != null)
+                    ex = refEx.InnerException;
+
                 arg_exc.ToJS(ex);
             }
         }

src/tests/BuildWasmApps/Wasm.Build.Tests/WasmBuildAppTest.cs

@@ -55,6 +55,18 @@ public static int Main()
                     }
                 }", buildArgs, host, id);
 
+        [Theory]
+        [MemberData(nameof(MainMethodTestData), parameters: new object[] { /*aot*/ false, RunHost.All })]
+        public void ExceptionFromMain(BuildArgs buildArgs, RunHost host, string id)
+            => TestMain("main_exception", """
+                using System;
+                using System.Threading.Tasks;
+
+                public class TestClass {
+                    public static int Main() => throw new Exception("MessageFromMyException");
+                }
+                """, buildArgs, host, id, expectedExitCode: 71, expectedOutput: "Error: MessageFromMyException");
+
         private static string s_bug49588_ProgramCS = @"
             using System;
             public class TestClass {
@@ -165,7 +177,9 @@ protected void TestMain(string projectName,
               RunHost host,
               string id,
               string extraProperties = "",
-              bool? dotnetWasmFromRuntimePack = null)
+              bool? dotnetWasmFromRuntimePack = null,
+              int expectedExitCode = 42,
+              string expectedOutput = "Hello, World!")
         {
             buildArgs = buildArgs with { ProjectName = projectName };
             buildArgs = ExpandBuildArgs(buildArgs, extraProperties);
@@ -179,8 +193,8 @@ protected void TestMain(string projectName,
                                 InitProject: () => File.WriteAllText(Path.Combine(_projectDir!, "Program.cs"), programText),
                                 DotnetWasmFromRuntimePack: dotnetWasmFromRuntimePack));
 
-            RunAndTestWasmApp(buildArgs, expectedExitCode: 42,
-                                test: output => Assert.Contains("Hello, World!", output), host: host, id: id);
+            RunAndTestWasmApp(buildArgs, expectedExitCode: expectedExitCode,
+                                test: output => Assert.Contains(expectedOutput, output), host: host, id: id);
         }
     }
 }