Unable to Specify that Proxy should listen on an address

[oliverisaac]

If one tries to start the martian proxy such that it listens on only localhost then an error is thrown:

$ $GOPATH/bin/proxy -api-addr=localhost:9090
2021/03/31 12:59:42 strconv.Atoi: parsing "localhost9090": invalid syntax

martian/cmd/proxy/main.go

Lines 337 to 348 in dacbe1a

	if *apiAddr != "" {
	apip := strings.Replace(*apiAddr, ":", "", 1)
	port, err := strconv.Atoi(apip)
	if err != nil {
	log.Fatal(err)
	}
	// Forward traffic that pattern matches in http.DefaultServeMux
	apif := servemux.NewFilter(mux)
	apif.SetRequestModifier(mapi.NewForwarder("", port))
	topg.AddRequestModifier(apif)
	}