Add debug logging to golang side

main.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"github.com/golang/protobuf/proto"
 	"github.com/ry/v8worker2"
+	"io/ioutil"
 	"log"
 	"os"
 	"runtime/pprof"
@@ -34,6 +35,11 @@ func main() {
 	}
 	args = v8worker2.SetFlags(args)
 
+	// Unless the debug flag is specified, discard logs.
+	if !*flagDebug {
+		log.SetOutput(ioutil.Discard)
+	}
+
 	// Maybe start Golang CPU profiler.
 	// Use --prof for profiling JS.
 	if *flagGoProf != "" {

os.go

@@ -3,6 +3,7 @@ package main
 import (
 	"github.com/golang/protobuf/proto"
 	"io/ioutil"
+	"log"
 	"net/url"
 	"os"
 	"path"
@@ -35,6 +36,9 @@ func InitOS() {
 
 func ResolveModule(moduleSpecifier string, containingFile string) (
 	moduleName string, filename string, err error) {
+
+	log.Printf("ResolveModule %s %s", moduleSpecifier, containingFile)
+
 	moduleUrl, err := url.Parse(moduleSpecifier)
 	if err != nil {
 		return