fix: native methods expecting a NSError arg will now throw a JS exception if the error arg is not passed (#311)

Author: farfromrefug

NativeScript/runtime/Interop.mm

@@ -1574,7 +1574,38 @@ inline bool isBool() {
         NSError* error = errorPtr[0];
         std::free(errorRef);
         if (error) {
-            throw NativeScriptException([[error localizedDescription] UTF8String]);
+            // Create JS Error with localizedDescription, attach code, domain and nativeException,
+            // and throw it into V8 so JS catch handlers receive it (with proper stack).
+            Isolate* isolate = methodCall.context_->GetIsolate();
+            Local<Context> context = isolate->GetCurrentContext();
+
+            Local<Value> jsErrVal = Exception::Error(tns::ToV8String(isolate, [[error localizedDescription] UTF8String]));
+            if (jsErrVal.IsEmpty() || !jsErrVal->IsObject()) {
+                // Fallback: if for some reason we cannot create an Error object, throw a generic NativeScriptException
+                throw NativeScriptException([[error localizedDescription] UTF8String]);
+            }
+
+            Local<Object> jsErrObj = jsErrVal.As<Object>();
+
+            // Attach the NSError code (number) and domain (string)
+            jsErrObj->Set(context, tns::ToV8String(isolate, "code"), Number::New(isolate, (double)[error code])).FromMaybe(false);
+            if (error.domain) {
+                jsErrObj->Set(context, tns::ToV8String(isolate, "domain"), tns::ToV8String(isolate, [error.domain UTF8String])).FromMaybe(false);
+            } else {
+                jsErrObj->Set(context, tns::ToV8String(isolate, "domain"), Null(isolate)).FromMaybe(false);
+            }
+
+            // Wrap the native NSError instance into a JS object and attach as nativeException
+            ObjCDataWrapper* wrapper = new ObjCDataWrapper(error);
+            Local<Value> nativeWrapper = ArgConverter::CreateJsWrapper(context, wrapper, Local<Object>(), true);
+            jsErrObj->Set(context, tns::ToV8String(isolate, "nativeException"), nativeWrapper).FromMaybe(false);
+
+            // Ensure the Error has a proper 'name' property.
+            jsErrObj->Set(context, tns::ToV8String(isolate, "name"), tns::ToV8String(isolate, "NSError")).FromMaybe(false);
+
+            // Throw the JS Error with full stack information — V8 will populate the stack for the created Error object.
+            isolate->ThrowException(jsErrObj);
+            return Local<Value>();
         }
     }
 

TestRunner/app/tests/ApiTests.js

@@ -321,6 +321,52 @@ describe(module.id, function () {
             JSApi.new().methodError(1);
         }).toThrowError(/JS error/);
     });
+    it("throws JS Error wrapping NSError when no error arg is passed", function () {
+        var isThrown = false;
+        try {
+            // TNSApi.methodError(errorCode, error: NSError**)
+            // Calling without the last interop.Reference should cause the runtime to
+            // throw a JS Error that wraps the native NSError (for non-zero errorCode).
+            TNSApi.new().methodError(1);
+        } catch (e) {
+            isThrown = true;
+
+            // Basic shape checks
+            expect(e).toBeDefined();
+            expect(e.message).toEqual(jasmine.any(String));
+            expect(e.stack).toEqual(jasmine.any(String)); // proper JS stack present
+
+            // Fields we attach from the NSError
+            expect(e.code).toBe(1);
+            expect(e.domain).toBe("TNSErrorDomain");
+
+            // nativeException should be the wrapped NSError object
+            expect(e.nativeException).toBeDefined();
+            // The wrapped object should behave like an NSError proxy/wrapper
+            // (we assert existence of localizedDescription property)
+            expect(typeof e.nativeException.localizedDescription).toBe('string');
+        } finally {
+            expect(isThrown).toBe(true);
+        }
+    });
+
+    it("does not throw when error arg is passed and the error ref is filled", function () {
+        // When the caller passes an interop.Reference() as the last argument,
+        // the runtime should not throw; it should return the method's boolean
+        // result and write the NSError into the reference.
+        var errorRef = new interop.Reference();
+        var result = TNSApi.new().methodError(1, errorRef);
+
+        // The method returns false for non-zero error code
+        expect(result).toBe(false);
+
+        // The errorRef should be populated with an NSError
+        expect(errorRef.value instanceof NSError).toBe(true);
+
+        // Validate the NSError contents
+        expect(errorRef.value.code).toBe(1);
+        expect(errorRef.value.domain).toBe("TNSErrorDomain");
+    });
 
 //     it("NSErrorExpose", function () {
 //         var JSApi = TNSApi.extend({