spider fallback, need get grab instance from there

[EnzoRondo]

https://docs.grablib.org/en/latest/spider/error_handling.html#handling-of-failed-tasks says:

When the task is aborted and there is method with name task__fallback then it is called and receives the failed task as first argument.

works fine, but I need also get grab instance of failed task. because my goal to get error text (like "domain not resolved error") and I can't find this information in task properties

what I have

    def task_test_fallback(self, task):
        print("task data is ", task)
        # now I need grab instance data, but it's not possible to get it from here

what I need:

    def task_test_fallback(self, task, grab):
        print("grab data is ", grab)
        # this idea is not works, try it yourself to be sure