ensure backwards compatitibility

freqtrade/freqai/data_kitchen.py

@@ -1156,6 +1156,7 @@ class FreqaiDataKitchen:
             valid_strs = [f"%-{pair}", f"%{pair}", f"%_{pair}"]
             pair_cols = [col for col in dataframe.columns if
                          any(substr in col for substr in valid_strs)]
+            if pair_cols:
                 pair_cols.insert(0, 'date')
             corr_dataframes[pair] = dataframe.filter(pair_cols, axis=1)
 

freqtrade/freqai/freqai_interface.py

@@ -759,7 +759,7 @@ class IFreqaiModel(ABC):
                                "is included in the column names when you are creating features "
                                "in `populate_any_indicators()`.")
             self.get_corr_dataframes = not bool(self.corr_dataframes)
-        else:
+        elif self.corr_dataframes:
             dataframe = dk.attach_corr_pair_columns(
                 dataframe, self.corr_dataframes, dk.pair)