Fix compilation errors in py_loader_port.c

- Replace Py_XDecRef with Py_DecRef using explicit NULL checks
  (Py_XDecRef is not available on all platforms)
- Implement PyExc_MemoryErrorPtr in py_loader_symbol_fallback.c
  following the existing pattern for other exception types

Author: claude

source/loaders/py_loader/source/py_loader_port.c

@@ -602,7 +602,10 @@ static void *py_loader_port_await_resolve(void *result, void *data)
 		PyObject *args = PyTuple_Pack(3, asyncio_loop, ctx->future, py_result);
 		PyObject *call_result = PyObject_Call(future_resolve_func, args, NULL);
 
-		Py_XDecRef(call_result);
+		if (call_result != NULL)
+		{
+			Py_DecRef(call_result);
+		}
 		Py_DecRef(args);
 		Py_DecRef(future_resolve_func);
 	}
@@ -660,7 +663,10 @@ static void *py_loader_port_await_reject(void *result, void *data)
 		PyObject *args = PyTuple_Pack(3, asyncio_loop, ctx->future, py_exception);
 		PyObject *call_result = PyObject_Call(future_reject_func, args, NULL);
 
-		Py_XDecRef(call_result);
+		if (call_result != NULL)
+		{
+			Py_DecRef(call_result);
+		}
 		Py_DecRef(args);
 		Py_DecRef(future_reject_func);
 	}
@@ -761,7 +767,10 @@ static PyObject *py_loader_port_await(PyObject *self, PyObject *var_args)
 	if (future_create_func == NULL || !PyCallable_Check(future_create_func))
 	{
 		PyErr_SetString(PyExc_RuntimeErrorPtr(), "Failed to get future_create function");
-		Py_XDecRef(future_create_func);
+		if (future_create_func != NULL)
+		{
+			Py_DecRef(future_create_func);
+		}
 		goto cleanup_args;
 	}
 

source/loaders/py_loader/source/py_loader_symbol_fallback.c

@@ -41,6 +41,7 @@ static PyObject **PyExc_FileNotFoundErrorStructPtr = NULL;
 static PyObject **PyExc_TypeErrorStructPtr = NULL;
 static PyObject **PyExc_ValueErrorStructPtr = NULL;
 static PyObject **PyExc_RuntimeErrorStructPtr = NULL;
+static PyObject **PyExc_MemoryErrorStructPtr = NULL;
 static PyObject *Py_FalseStructPtr = NULL;
 static PyObject *Py_TrueStructPtr = NULL;
 #endif
@@ -183,6 +184,14 @@ int py_loader_symbol_fallback_initialize(dynlink py_library)
 
 	dynlink_symbol_uncast_type(address, PyObject **, PyExc_RuntimeErrorStructPtr);
 
+	/* PyExc_MemoryError */
+	if (dynlink_symbol(py_library, "PyExc_MemoryError", &address) != 0)
+	{
+		return 1;
+	}
+
+	dynlink_symbol_uncast_type(address, PyObject **, PyExc_MemoryErrorStructPtr);
+
 	/* Py_False */
 	if (dynlink_symbol(py_library, "_Py_FalseStruct", &address) != 0)
 	{
@@ -337,6 +346,15 @@ PyObject *PyExc_RuntimeErrorPtr(void)
 #endif
 }
 
+PyObject *PyExc_MemoryErrorPtr(void)
+{
+#if defined(_WIN32) && defined(_MSC_VER)
+	return *PyExc_MemoryErrorStructPtr;
+#else
+	return PyExc_MemoryError;
+#endif
+}
+
 PyObject *Py_ReturnNone(void)
 {
 #if defined(_WIN32) && defined(_MSC_VER)