Daemon Race for client count

[mohamedmansour]

This only happens on startup while running --race, just once it happens

==================
WARNING: DATA RACE
Read at 0x00c00020a450 by goroutine 98:
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).handleInitialData.func1()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:545 +0xc71
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Client).readPump()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/client.go:134 +0x57c
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).serveWebSocket·dwrap·7()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:347 +0x39

Previous write at 0x00c00020a450 by goroutine 84:
  runtime.mapassign_fast64()
      /usr/local/go/src/runtime/map_fast64.go:92 +0x0
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).listen()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:258 +0x1ea
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).ListenAndServe·dwrap·5()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:319 +0x39

Goroutine 98 (running) created at:
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).serveWebSocket()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:347 +0x405
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).serveWebSocket-fm()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:331 +0x57
  net/http.HandlerFunc.ServeHTTP()
      /usr/local/go/src/net/http/server.go:2046 +0x4d
  net/http.(*ServeMux).ServeHTTP()
      /usr/local/go/src/net/http/server.go:2424 +0xc5
  net/http.serverHandler.ServeHTTP()
      /usr/local/go/src/net/http/server.go:2878 +0x89a
  net/http.(*conn).serve()
      /usr/local/go/src/net/http/server.go:1929 +0x12e4
  net/http.(*Server).Serve·dwrap·82()
      /usr/local/go/src/net/http/server.go:3033 +0x58

Goroutine 84 (running) created at:
  github.com/mohamedmansour/ethereum-burn-stats/daemon/hub.(*Hub).ListenAndServe()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/hub/hub.go:319 +0xa4
  github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd.root()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd/root.go:90 +0xc9
  github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd.newRootCmd.func1()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd/root.go:42 +0x2c6
  github.com/spf13/cobra.(*Command).execute()
      /go/pkg/mod/github.com/spf13/[email protected]/command.go:856 +0xa7d
  github.com/spf13/cobra.(*Command).ExecuteC()
      /go/pkg/mod/github.com/spf13/[email protected]/command.go:974 +0x5da
  github.com/spf13/cobra.(*Command).Execute()
      /go/pkg/mod/github.com/spf13/[email protected]/command.go:902 +0x29
  github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd.Execute()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/cmd/root.go:100 +0x20
  main.main()
      /go/src/github.com/mohamedmansour/ethereum-burn-stats/daemon/main.go:8 +0x24
==================