`logic_error` on `BT::BehaviorTreeFactory::registerNodeType()` When Setting `InputPort` `default_value` to `nullptr` After Commit 789ce6ea0ad3627923bd2389b8fb9199ffab6d84

[KentaKato]

Following the changes made in commit 789ce6e, setting the default_value of an InputPort to nullptr now results in a logic_error during the execution of BT::BehaviorTreeFactory::registerNodeType().

The program terminates with the following error message:

terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string::_M_construct null not valid
Aborted (core dumped)

This issue indicates a problem with handling nullptr as the default_value for InputPort in the context of BT::BehaviorTreeFactory::registerNodeType(), which appears to be a new behavior following the specified commit.

[facontidavide]

Please provide a unit test. Also what is the type of the port?
What is your intent with a nullptr?

[KentaKato]

@facontidavide
Thank you for your prompt reply.

I cannot provide a unit test right away, but I will first address the latter part of your question.

I had set nullptr as the default value for shared_ptr as shown below. T is a class with a high instantiation cost, and an instance is only created within the Node if it's nullptr. Is this usage unexpected?

    static BT::PortsList providedPorts()
    {
        return {
            BT::InputPort<std::shared_ptr<T>>("test", nullptr, "description")};
    };

[facontidavide]

Ok, let me have a look

[facontidavide]

Check 83fce13

If the problem persists, please tell me how to extend the unit test Default_Issues_767_768 to cover your case.

[KentaKato]

@facontidavide
Thank you for addressing this so quickly. I've verified that the problem has been solved.