Factor TimeseriesNotFound to top level

TO CHERRY into #486

piker/data/history.py

@@ -57,6 +57,7 @@
 from ..brokers._util import (
     DataUnavailable,
 )
+from ..storage import TimeseriesNotFound
 
 if TYPE_CHECKING:
     from bidict import bidict
@@ -690,13 +691,18 @@ async def tsdb_backfill(
         # but if not then below the remaining history can be lazy
         # loaded?
         fqme: str = mkt.fqme
-        tsdb_entry: tuple | None =  await storage.load(
-            fqme,
-            timeframe=timeframe,
-        )
-
         last_tsdb_dt: datetime | None = None
-        if tsdb_entry:
+        try:
+            tsdb_entry: tuple | None =  await storage.load(
+                fqme,
+                timeframe=timeframe,
+            )
+        except TimeseriesNotFound:
+            log.warning(
+                f'No timeseries yet for {fqme}'
+            )
+
+        else:
             (
                 tsdb_history,
                 first_tsdb_dt,
@@ -963,7 +969,8 @@ async def manage_history(
             sub_for_broadcasts=False,
 
         ) as sample_stream:
-            # register 1s and 1m buffers with the global incrementer task
+            # register 1s and 1m buffers with the global
+            # incrementer task
             log.info(f'Connected to sampler stream: {sample_stream}')
 
             for timeframe in [60, 1]:

piker/storage/__init__.py

@@ -139,6 +139,13 @@ async def write_ohlcv(
         ...
 
 
+class TimeseriesNotFound(Exception):
+    '''
+    No timeseries entry can be found for this backend.
+
+    '''
+
+
 class StorageConnectionError(ConnectionError):
     '''
     Can't connect to the desired tsdb subsys/service.

piker/storage/nativedb.py

@@ -19,7 +19,8 @@
             call a poor man's tsdb).
 
 AKA a `piker`-native file-system native "time series database"
-without needing an extra process and no standard TSDB features, YET!
+without needing an extra process and no standard TSDB features,
+YET!
 
 '''
 # TODO: like there's soo much..
@@ -67,17 +68,12 @@
 from piker.data import def_iohlcv_fields
 from piker.data import ShmArray
 from piker.log import get_logger
+from . import TimeseriesNotFound
 
 
 log = get_logger('storage.nativedb')
 
 
-class TimeseriesNotFound(Exception):
-    '''
-    No timeseries entry can be found for this backend.
-
-    '''
-
 # NOTE: thanks to this SO answer for the below conversion routines
 # to go from numpy struct-arrays to polars dataframes and back:
 # https://stackoverflow.com/a/72054819