Don't attempt to calculate funding fees when the initial timeframe hasn't been exceeded.

freqtrade/exchange/exchange.py

@@ -1865,6 +1865,7 @@ class Exchange:
         mark_rates = candle_histories[mark_comb]
 
         df = funding_rates.merge(mark_rates, on='date', how="inner", suffixes=["_fund", "_mark"])
+        if not df.empty:
             df = df[(df['date'] >= open_date) & (df['date'] <= close_date)]
             fees = sum(df['open_fund'] * df['open_mark'] * amount)