Refactor: proper error handling.

bilibili/streaming.go

@@ -42,7 +42,7 @@ func (b Bilibili) CopyLiveStream(
 
 	// 404 when not streaming
 	if resp.StatusCode == http.StatusNotFound {
-		return ErrRoomIsClosed
+		return fmt.Errorf("live is not started or the room does not exist")
 	}
 
 	err = validateHttpStatus(resp)

recording/errors.go

@@ -0,0 +1,33 @@
+package recording
+
+import "fmt"
+
+/*
+Task errors.
+*/
+
+type RecoverableTaskError struct {
+	err     error
+	message string
+}
+
+func (e *RecoverableTaskError) Error() string {
+	return fmt.Sprintf("%v: %v", e.message, e.err)
+}
+
+func NewRecoverableTaskError(message string, err error) error {
+	return &RecoverableTaskError{message: message, err: err}
+}
+
+type UnrecoverableTaskError struct {
+	err     error
+	message string
+}
+
+func (e *UnrecoverableTaskError) Error() string {
+	return fmt.Sprintf("%v: %v", e.message, e.err)
+}
+
+func NewUnrecoverableTaskError(message string, err error) error {
+	return &UnrecoverableTaskError{message: message, err: err}
+}