[Bug] safeline-chaos fails update with the following issue server.go:83

[brwatters]

What happened?

panic: runtime error: invalid memory address or nil pointer dereference
goroutine ... running:
git.in.chaitin.net/safeline-ce/challenge/server.(*APIServer).Shutdown(0xc000... )
/app/server/server.go:83 +0xdb
main.gracefulShutdown(...)

How we reproduce?

1. ...attempt container update this error is produced each time
2. ...
3. ...

Expected behavior

No response

Error log

panic: runtime error: invalid memory address or nil pointer dereference
goroutine ... running:
git.in.chaitin.net/safeline-ce/challenge/server.(*APIServer).Shutdown(0xc000... )
/app/server/server.go:83 +0xdb
main.gracefulShutdown(...)