jsonImporter fixups

1) Tolerate lists with no entries
2) Exit with error messages instead of Chk.NoError() in main()
3) General variable names
4) Use json.NewDecoder() instead of reading all data into memory again.
5) Idiomatic fixes.

Addresses issue #20

clients/jsonImporter/jsonImporter.go

@@ -4,42 +4,44 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-	"io/ioutil"
+	"log"
 	"net/http"
 
 	"github.com/attic-labs/noms/chunks"
 	"github.com/attic-labs/noms/datas"
-	"github.com/attic-labs/noms/dbg"
 	"github.com/attic-labs/noms/types"
 )
 
 func nomsValueFromObject(o interface{}) types.Value {
-	switch oo := o.(type) {
+	switch o := o.(type) {
 	case string:
-		return types.NewString(oo)
+		return types.NewString(o)
 	case bool:
-		return types.Bool(oo)
+		return types.Bool(o)
 	case float64:
-		return types.Float64(oo)
+		return types.Float64(o)
 	case nil:
 		return nil
 	case []interface{}:
 		out := types.NewList()
-		for _, v := range oo {
-			out = out.Append(nomsValueFromObject(v))
+		for _, v := range o {
+			nv := nomsValueFromObject(v)
+			if nv != nil {
+				out = out.Append(nv)
+			}
 		}
 		return out
 	case map[string]interface{}:
 		out := types.NewMap()
-		for k, v := range oo {
+		for k, v := range o {
 			nv := nomsValueFromObject(v)
 			if nv != nil {
 				out = out.Set(types.NewString(k), nv)
 			}
 		}
 		return out
 	default:
-		fmt.Println(oo, "is of a type I don't know how to handle")
+		fmt.Println(o, "is of a type I don't know how to handle")
 	}
 	return nil
 }
@@ -60,24 +62,27 @@ func main() {
 	}
 
 	res, err := http.Get(url)
-	dbg.Chk.NoError(err)
-
-	gameEventsJSON, err := ioutil.ReadAll(res.Body)
-	res.Body.Close()
-	dbg.Chk.NoError(err)
+	defer res.Body.Close()
+	if err != nil {
+		log.Fatalf("Error fetching %s: %+v\n", url, err)
+	} else if res.StatusCode != 200 {
+		log.Fatalf("Error fetching %s: %s\n", url, res.Status)
+	}
 
-	var events interface{}
-	err = json.Unmarshal(gameEventsJSON, &events)
-	dbg.Chk.NoError(err)
+	var jsonObject interface{}
+	err = json.NewDecoder(res.Body).Decode(&jsonObject)
+	if err != nil {
+		log.Fatalln("Error decoding JSON: ", err)
+	}
 
 	ds := datas.NewDataStore(cs)
 	roots := ds.Roots()
 
-	gameEvents := nomsValueFromObject(events)
+	value := nomsValueFromObject(jsonObject)
 
 	ds.Commit(datas.NewRootSet().Insert(
 		datas.NewRoot().SetParents(
 			roots.NomsValue()).SetValue(
-			gameEvents)))
+			value)))
 
 }