From 0277cd82ea66cd019138f0f45caaeed3b0afc187 Mon Sep 17 00:00:00 2001
From: hroff-1902 <hroff_raeyd9tzpttf@mail.ru>
Date: Mon, 16 Dec 2019 23:25:57 +0300
Subject: [PATCH] Make mypy happy

---
 freqtrade/data/history.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/freqtrade/data/history.py b/freqtrade/data/history.py
index 79500c512..2c01f9f48 100644
--- a/freqtrade/data/history.py
+++ b/freqtrade/data/history.py
@@ -295,6 +295,11 @@ def _download_pair_history(datadir: Path,
     :param timerange: range of time to download
     :return: bool with success state
     """
+    if not exchange:
+        raise OperationalException(
+            "Exchange needs to be initialized when downloading pair history data"
+        )
+
     try:
         logger.info(
             f'Download history data for pair: "{pair}", timeframe: {timeframe} '