The new feature also needs to be mentioned in the ./docs/cargo_features.md file.

@mockersf
Curious on what your thoughts are with this and how #2241 interact?
Specifically because my PR changes the default behavior to not panic, so the panic handler would only work where someone specifies

.on_err(CommandErrorHandler::panic())

which, I have a feeling will be few and far between.

It's probably a better approach to have the Command trait be defined as something like:

struct CommandArgs<'a> {
    world: &'a mut World,
    system_name: Cow<'static, str>,
}

trait Command  {
    fn write(self: Box<Self>, args: CommandArgs);
}

So that way all commands (and error handlers) can have the system name correctly propagated to them?

Curious on what your thoughts are with this and how #2241 interact?

I think this'll definitely to be looked at after #2241 has been merged, moved it to draft

It's probably a better approach to have the Command trait be defined as something like:

struct CommandArgs<'a> {
    world: &'a mut World,
    system_name: Cow<'static, str>,
}

trait Command  {
    fn write(self: Box<Self>, args: CommandArgs);
}

So that way all commands (and error handlers) can have the system name correctly propagated to them?

Or having the system name in the CommandError struct?

Or having the system name in the CommandError struct?

Yep, it'll be there to.
However, to have it even be passed to the error handler, it needs to be passed though to Command::write as well.