refactor: don't block when polling ircCommandQueue

[iProdigy]

Prerequisites for Code Changes

• This pull request follows the code style of the project
• I have tested this feature

Issues Fixed

Avoids the following exception from being logged on ITwitchClient#close:

[ERROR] c.g.t.chat.TwitchChat - Chat: Unexpected error in worker thread
java.lang.InterruptedException: null
	at java.base/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:1668)
	at java.base/java.util.concurrent.ArrayBlockingQueue.poll(ArrayBlockingQueue.java:435)
	at com.github.twitch4j.chat.TwitchChat.lambda$new$0(TwitchChat.java:349)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
	at java.base/java.lang.Thread.run(Thread.java:832)

(the thread still shuts down gracefully, just the exception can appear spooky for a normal operation)

Changes Proposed

• Do not block when polling ircCommandQueue for an element (so no more InterruptedException would be fired)

Additional Information

flushCommand is called frequently enough that the blocking poll is not needed

 

Thanks to 쩌리곰#3393 for reporting