binance: raise `NoData` on null hist arrays

Like we do with other history backends to indicate lack of a data set.
This avoids any raise that will will bring down the backloader task with
some downstream error.

Raise a `ValueError` on no time index for now.

piker/brokers/binance/feed.py

@@ -48,6 +48,7 @@ import tractor
 
 from piker.brokers import (
     open_cached_client,
+    NoData,
 )
 from piker._cacheables import (
     async_lifo_cache,
@@ -254,22 +255,28 @@ async def open_history_client(
 
             # NOTE: always query using their native symbology!
             mktid: str = mkt.bs_mktid
-            array = await client.bars(
+            array: np.ndarray = await client.bars(
                 mktid,
                 start_dt=start_dt,
                 end_dt=end_dt,
             )
+            if array.size == 0:
+                raise NoData('No frame for {start_dt} -> {end_dt}\n')
+
             times = array['time']
-            if (
-                end_dt is None
-            ):
-                inow = round(time.time())
+            if not times.any():
+                raise ValueError(
+                    'Bad frame with null-times?\n\n'
+                    f'{times}'
+                )
+
+            if end_dt is None:
+                inow: int = round(time.time())
                 if (inow - times[-1]) > 60:
                     await tractor.pause()
 
             start_dt = from_timestamp(times[0])
             end_dt = from_timestamp(times[-1])
-
             return array, start_dt, end_dt
 
         yield get_ohlc, {'erlangs': 3, 'rate': 3}