chore: minor adjustments for clarity

freqtrade/data/converter/converter.py

@@ -38,6 +38,7 @@ def ohlcv_to_dataframe(
     cols = DEFAULT_DATAFRAME_COLUMNS
     df = DataFrame(ohlcv, columns=cols)
 
+    # Floor date to seconds to account for exchange imprecisions
     df["date"] = to_datetime(df["date"], unit="ms", utc=True).dt.floor("s")
 
     # Some exchanges return int values for Volume and even for OHLC.

freqtrade/data/dataprovider.py

@@ -350,7 +350,7 @@ class DataProvider:
 
     def __fix_funding_rate_timeframe(
         self, pair: str, timeframe: str | None, candle_type: str
-    ) -> str:
+    ) -> str | None:
         if (
             candle_type == CandleType.FUNDING_RATE
             and (ff_tf := self.get_funding_rate_timeframe()) != timeframe