context: pass context to the OnError middleware

bot.go

@@ -65,11 +65,9 @@ type Bot struct {
 	URL     string
 	Updates chan Update
 	Poller  Poller
-	OnError func(error)
-
-	handlers   map[string]HandlerFunc
-	middleware map[string][]MiddlewareFunc
+	OnError func(error, Context)
 
+	handlers    map[string]HandlerFunc
 	synchronous bool
 	verbose     bool
 	parseMode   ParseMode
@@ -102,10 +100,10 @@ type Settings struct {
 	// will be able to override the default mode by passing a new one.
 	ParseMode ParseMode
 
-	// OnError is a callback function that will get called
-	// on errors resulted from the handler. It is used as
-	// post-middleware function.
-	OnError func(error)
+	// OnError is a callback function that will get called on errors
+	// resulted from the handler. It is used as post-middleware function.
+	// Notice that context can be nil.
+	OnError func(error, Context)
 
 	// HTTP Client used to make requests to telegram api
 	Client *http.Client

bot_test.go

@@ -348,14 +348,15 @@ func TestBotOnError(t *testing.T) {
 	}
 
 	var ok bool
-	b.OnError = func(err error) {
+	b.OnError = func(err error, c Context) {
+		assert.Equal(t, b, c.(*nativeContext).b)
 		assert.NotNil(t, err)
 		ok = true
 	}
 
 	b.runHandler(func(c Context) error {
 		return errors.New("not nil")
-	}, &nativeContext{})
+	}, &nativeContext{b: b})
 
 	assert.True(t, ok)
 }

util.go

@@ -11,7 +11,7 @@ import (
 func (b *Bot) debug(err error) {
 	err = errors.WithStack(err)
 	if b.OnError != nil {
-		b.OnError(err)
+		b.OnError(err, nil)
 	} else {
 		log.Printf("%+v\n", err)
 	}
@@ -30,8 +30,10 @@ func (b *Bot) deferDebug() {
 func (b *Bot) runHandler(h HandlerFunc, c Context) {
 	f := func() {
 		defer b.deferDebug()
-		if err := h(c); err != nil && err != ErrSkip {
-			b.OnError(err)
+		if err := h(c); err != nil {
+			if err != ErrSkip {
+				b.OnError(err, c)
+			}
 		}
 	}
 	if b.synchronous {