[wasm] fix marshaling Error to C# as JSType.Any (#79352)

Co-authored-by: pavelsavara <[email protected]>

Author: github-actions[bot]

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportExportTest.cs

@@ -1363,6 +1363,14 @@ public void JsExportThrows()
             Assert.Contains("-t-e-s-t-", ex.Message);
         }
 
+        [Fact]
+        public void JSImportReturnError()
+        {
+            var err = JavaScriptTestHelper.returnError() as Exception;
+            Assert.NotNull(err);
+            Assert.Contains("this-is-error", err.Message);
+        }
+
         [Fact]
         public void JsExportCatchToString()
         {

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs

@@ -67,6 +67,10 @@ public static DateTime Now()
         [return: JSMarshalAs<JSType.Discard>]
         internal static partial void throw0();
 
+        [JSImport("returnError", "JavaScriptTestHelper")]
+        [return: JSMarshalAs<JSType.Any>]
+        internal static partial object returnError();
+
         [JSImport("echo1", "JavaScriptTestHelper")]
         [return: JSMarshalAs<JSType.Promise<JSType.Void>>]
         internal static partial Task echo1_Task([JSMarshalAs<JSType.Promise<JSType.Void>>] Task arg1);

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.mjs

@@ -110,6 +110,10 @@ export function throw0fn() {
     throw new Error('throw-0-msg');
 }
 
+export function returnError() {
+    return new Error('this-is-error');
+}
+
 export function catch1toString(message, functionName) {
     const JavaScriptTestHelper = dllExports.System.Runtime.InteropServices.JavaScript.Tests.JavaScriptTestHelper;
     const fn = JavaScriptTestHelper[functionName];

src/mono/wasm/runtime/marshal-to-cs.ts

@@ -449,9 +449,7 @@ function _marshal_cs_object_to_cs(arg: JSMarshalerArgument, value: any): void {
                 set_arg_date(arg, value);
             }
             else if (value instanceof Error) {
-                set_arg_type(arg, MarshalerType.JSException);
-                const js_handle = mono_wasm_get_js_handle(value);
-                set_js_handle(arg, js_handle);
+                marshal_exception_to_cs(arg, value);
             }
             else if (value instanceof Uint8Array) {
                 marshal_array_to_cs_impl(arg, value, MarshalerType.Byte);