Check if channel is open before injecting

[linsaftw]

Some forks like FlameCord have integrated anti-bot features to block connections early.

By default, Floodgate runs anyways, which not only makes bot attacks affect the server when Floodgate is instaled, but also generate an exception.

This fixes the issue.

[Tim203]

It is interesting to me that those features are called early enough that the channel initializer has not yet run, but late enough that it still tries to invoke the channel initializer.
However, this specific request seems reasonable enough.
I'll add a comment to the code saying that it's needed for some Bungee forks, because generally speaking it is not needed to check if a channel is closed as early as for a SeverBootstrap#childHandler

[linsaftw]

It is interesting to me that those features are called early enough that the channel initializer has not yet run, but late enough that it still tries to invoke the channel initializer. However, this specific request seems reasonable enough. I'll add a comment to the code saying that it's needed for some Bungee forks, because generally speaking it is not needed to check if a channel is closed as early as for a SeverBootstrap#childHandler

Yes they are run on the pipeline entry initChannel() from PipelineUtils, which cannot cancel next pipeline entries as the Floodgate one.