update readme, unmarshal errors properly

README.md

 Image Board
 -----------
-Taggable image board in 1209 lines of code.
+Taggable image board in 1272 lines of code.
 
 Get it:
 ```shell

client/request.go

@@ -3,9 +3,11 @@ package client
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
+	"random.chars.jp/git/image-board/api"
 )
 
 func (r *Remote) send(req *http.Request) (*http.Response, error) {
@@ -94,7 +96,19 @@ func unmarshal(reader io.ReadCloser, v interface{}) error {
 			fmt.Printf("Error closing reader after unmarshalling, %s\n", err)
 		}
 	}()
-	if err := json.NewDecoder(reader).Decode(v); err != nil {
+
+	var data []byte
+	if d, err := io.ReadAll(reader); err != nil {
+		return err
+	} else {
+		data = d
+	}
+
+	if err := json.Unmarshal(data, v); err != nil {
+		var errPayload api.Error
+		if tryErr := json.Unmarshal(data, &errPayload); tryErr == nil {
+			return errors.New(errPayload.Error)
+		}
 		return err
 	}
 	return nil