fix: cut-off (too short) timeframe-detail bug

If the detail data stops short, this shouldn't cause an exception.
instead, we should continue with "parent only" logic.

Author: xmatthias

freqtrade/optimize/backtesting.py

@@ -1649,7 +1649,7 @@ def time_pair_generator(
                     pair_detail = self.get_detail_data(pair, row)
                     if pair_detail is not None:
                         pair_detail_cache[pair] = pair_detail
-                    row = pair_detail_cache[pair][idx]
+                        row = pair_detail_cache[pair][idx]
 
                 is_last_row = current_time_det == end_date