bug: set connection variable to "false", before calling serverDidSendError or stompClientDisconnect

[JuyeonYu]

No description provided.

[WrathChaos]

Hello @JuyeonYu
Can you explain why we need it? What does it solve? What is the bug etc?

[JuyeonYu]

Hello @WrathChaos
this PR keeps consistency of the "connection" variable.
It is based on #123

When the client actively disconnect, the "connection" variable set to false.
So I double check the "connection" variable in stompClientDisconnect.
Because of preventing from reconnect and business logic etc.
Web socket is closed and "connection" variable is false.
It is happy case.

But the thing is different when the web socket is closed with some reasons.
Because the "connection" variable remains true even the web socket is closed.
So I have been manually changing the connection variable set to false in serverDidSendError and stompClientDisconnect.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.