electrum

commit 93d68a43611ec22369206f3edb03030b1d6fcb3e
parent 650225e238a1a9db07d713cf202f0ed1e51a92e7
Author: SomberNight <somber.night@protonmail.com>
Date:   Thu,  4 Jul 2019 19:55:03 +0200

exchange_rate: fix #5487

Diffstat:
M
electrum/exchange_rate.py
 | 
5
++++-

1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/electrum/exchange_rate.py b/electrum/exchange_rate.py
@@ -563,7 +563,8 @@ class FxThread(ThreadJob):
         self.logger.info(f"using exchange {name}")
         if self.config_exchange() != name:
             self.config.set_key('use_exchange', name, True)
-        self.exchange = class_(self.on_quotes, self.on_history)
+        assert issubclass(class_, ExchangeBase), f"unexpected type {class_} for {name}"
+        self.exchange = class_(self.on_quotes, self.on_history)  # type: ExchangeBase
         # A new exchange means new fx quotes, initially empty.  Force
         # a quote refresh
         self.trigger_update()
@@ -616,6 +617,8 @@ class FxThread(ThreadJob):
         # Use spot quotes in that case
         if rate == 'NaN' and (datetime.today().date() - d_t.date()).days <= 2:
             rate = self.exchange.quotes.get(self.ccy, 'NaN')
+            if rate is None:
+                rate = 'NaN'
             self.history_used_spot = True
         return Decimal(rate)