Noisy panic relating to updates

[directionless]

During the update process, launcher exits to let the service manager restart it. When this happens, there is a panic. While it's harmless, it's confusing noise.

ts=2020-08-14T13:10:44.5879133Z caller=handler.go:95 severity=info caller=handler.go:95 caller=handler.go:95 msg="signaling for a full restart" binary="C:\\Program Files\\Kolide\\Launcher-kolide-k2\\bin\\launcher.exe-updates\\1597410643\\launcher.exe"
ts=2020-08-14T13:10:44.5929137Z caller=launcher.go:121 severity=info caller=launcher.go:121 msg="beginnning shutdown via signal"
ts=2020-08-14T13:10:44.5939136Z caller=launcher.go:125 severity=info caller=launcher.go:125 msg=interrupted err=null
ts=2020-08-14T13:10:44.5939136Z caller=launcher.go:126 severity=debug caller=launcher.go:126 msg=interrupted err=null stack=<nil>
ts=2020-08-14T13:10:44.5949138Z caller=extension.go:135 severity=info caller=extension.go:135 msg="extension interrupted" err=null
ts=2020-08-14T13:10:44.5949138Z caller=extension.go:136 severity=debug caller=extension.go:136 msg="extension interrupted" err=null stack=<nil>
panic: close of closed channel

goroutine 37 [running]:
github.com/kolide/launcher/pkg/osquery/runtime.(*Runner).Shutdown(0xc0002454d0, 0x0, 0x0)
        /Users/seph/go/src/github.com/kolide/launcher/pkg/osquery/runtime/runtime.go:301 +0x56
main.createExtensionRuntime.func3(0x0, 0x0)
        /Users/seph/go/src/github.com/kolide/launcher/cmd/launcher/extension.go:139 +0x413
github.com/oklog/run.(*Group).Run(0xc0004e9d50, 0xc000244c30, 0xc00029a580)
        /Users/seph/go/pkg/mod/github.com/oklog/[email protected]/group.go:47 +0x15a
main.runLauncher(0xd49720, 0xc000244c30, 0xc000248550, 0xc000294240, 0x0, 0x0)
        /Users/seph/go/src/github.com/kolide/launcher/cmd/launcher/launcher.go:215 +0xb92
main.(*winSvc).Execute.func1(0xd49720, 0xc000244c30, 0xc000248550, 0xc00024e600, 0xc0002ae0c0)
        /Users/seph/go/src/github.com/kolide/launcher/cmd/launcher/svc_windows.go:108 +0x72
created by main.(*winSvc).Execute
        /Users/seph/go/src/github.com/kolide/launcher/cmd/launcher/svc_windows.go:107 +0x2d8