Shutdown failure

[robsimmonds]

Describe the bug
Backend does not aways shutdown when expected.
Also logs often state that some sessions have not been deleted due to a non-zero reference count which seems to be linked.

To Reproduce
Create multiple web connections to a single backend and have the connects shutdown and then reconnect is one time this happens.

Expected behavior
backend should die after last session has exited.

Platform info (please complete the following information):

• OS: [e.g. iOS] Ubuntu 20
• Browser [e.g. chrome, safari] chrome
• Version [e.g. 22]20

[robsimmonds]

Fixed by PR #1048