Gd<T>::bind_mut() failed, already bound

Reason

This error typically occurs when you attempt to get a mutable borrow (bind_mut()) of a Godot object that is already borrowed (either immutably or mutably). A common scenario is calling self.to_gd().bind_mut().

Solutions

Choose one of the following solutions:

1. (Recommended) Avoid self.to_gd().bind_mut(). Instead, use self.base_mut().some_base_method() to call methods on the base class mutably.

2. Change Function Signature: If you are passing the object to another function, consider passing a mutable reference to your struct type (&mut MyClass) instead of Gd<MyClass>, if feasible. This allows direct field access in the receiving function without needing bind_mut.

3. Use base_mut() Guard Carefully:

fn custom_method(&mut self) {
    let gd = self.to_gd();
    // guard
    let _guard = self.base_mut();
    // now it's safe to call bind
    gd.bind()
}