Move handle before check

Author: jiwaszki

include/pybind11/warnings.h

@@ -45,13 +45,12 @@ new_warning_type(handle scope, const char *name, handle base = PyExc_RuntimeWarn
                       + std::string(name) + "\" exists already.");
     }
     std::string full_name = scope.attr("__name__").cast<std::string>() + std::string(".") + name;
-    auto *new_ex = PyErr_NewException(const_cast<char *>(full_name.c_str()), base.ptr(), nullptr);
-    if (!new_ex) {
+    handle h(PyErr_NewException(full_name.c_str(), base.ptr(), nullptr));
+    if (!h) {
         raise_from(PyExc_SystemError,
                    "pybind11::warnings::new_warning_type(): PyErr_NewException() call failed.");
         throw error_already_set();
     }
-    handle h(new_ex);
     auto obj = reinterpret_steal<object>(h);
     scope.attr(name) = obj;
     return obj;