Event handlers are dropped twice

[matthunz]

Problem

In certain situations event handlers can be dropped twice and panic

Looks to come from

 #[doc(hidden)]
/// This should only be used by the `rsx!` macro.
pub fn __take(&self) -> ExternalListenerCallback<T> {
    self.callback
        .manually_drop()
        .expect("Signal has already been dropped")
        .expect("EventHandler was manually dropped")
}

Steps To Reproduce

Steps to reproduce the behavior:

• Create an event handler in rsx!
• TODO, still tracking this down

Expected behavior

Make sure event handlers don't drop twice.

Screenshots

If applicable, add screenshots to help explain your problem.

Environment:

• Dioxus version: v0.5.1
• Rust version: nightly
• OS info: MacOS
• App platform: Custom

Questionnaire

• [ ] I'm interested in fixing this myself but don't know where to start
• [*] I would like to fix and I (maybe) have a solution
• [ ] I don't have time to fix this right now, but maybe later