Move fiat_converter.convert_amount logic at the end of create_trade()

It is more important to save the trade in the DB than failing
because of the currency convertion. We do not know if
Pymarketcap() will not fail one day. Make sure the trade is saved before.

freqtrade/main.py

@@ -328,13 +328,26 @@ def create_trade(stake_amount: float, interval: int) -> bool:
             break
     else:
         return False
-
     # Calculate amount
     buy_limit = get_target_bid(exchange.get_ticker(pair))
     amount = stake_amount / buy_limit
 
     order_id = exchange.buy(pair, buy_limit, amount)
 
+    # Fee is applied twice because we make a LIMIT_BUY and LIMIT_SELL
+    trade = Trade(
+        pair=pair,
+        stake_amount=stake_amount,
+        amount=amount,
+        fee=exchange.get_fee(),
+        open_rate=buy_limit,
+        open_date=datetime.utcnow(),
+        exchange=exchange.get_name().upper(),
+        open_order_id=order_id
+    )
+    Trade.session.add(trade)
+    Trade.session.flush()
+
     fiat_converter = CryptoToFiatConverter()
     stake_amount_fiat = fiat_converter.convert_amount(
         stake_amount,
@@ -350,19 +363,7 @@ def create_trade(stake_amount: float, interval: int) -> bool:
         buy_limit, stake_amount, _CONF['stake_currency'],
         stake_amount_fiat, _CONF['fiat_display_currency']
     ))
-    # Fee is applied twice because we make a LIMIT_BUY and LIMIT_SELL
-    trade = Trade(
-        pair=pair,
-        stake_amount=stake_amount,
-        amount=amount,
-        fee=exchange.get_fee(),
-        open_rate=buy_limit,
-        open_date=datetime.utcnow(),
-        exchange=exchange.get_name().upper(),
-        open_order_id=order_id
-    )
-    Trade.session.add(trade)
-    Trade.session.flush()
+
     return True