Handle exceptions when updating currencies

commands.py

@@ -215,7 +215,12 @@ class Commands(object):
 
     def convert(self, expression, unit=None):
         c = Converter()
-        c.update_currencies(*self.rates.query())
+        try:
+            base, rates = self.rates.query()
+        except ExchangeRatesError:
+            pass
+        else:
+            c.update_currencies(base, rates)
         try:
             return c.convert(expression, unit)
         except ConverterError as e: