Add TimeseriesNotFound for fqme lookup failures

A common usage error is to run `piker anal mnq.cme.ib` where the CLI
passed fqme is not actually fully-qualified (in this case missing an
expiry token) and we get an underlying `FileNotFoundError` from the
`StorageClient.read_ohlcv()` call. In such key misses, scan the existing
`StorageClient._index` for possible matches and report in a `raise from`
the new error.

CHERRY into #486

piker/storage/cli.py

@@ -142,14 +142,21 @@ def anal(
     period: int = 60,
 
 ) -> np.ndarray:
+    '''
+    Anal-ysis is when you take the data do stuff to it, i think.
 
+    '''
     async def main():
         async with (
             open_piker_runtime(
+                # are you a bear or boi?
                 'tsdb_polars_anal',
                 debug_mode=True,
             ),
-            open_storage_client() as (mod, client),
+            open_storage_client() as (
+                mod,
+                client,
+            ),
         ):
             syms: list[str] = await client.list_keys()
             print(f'{len(syms)} FOUND for {mod.name}')

piker/storage/nativedb.py

@@ -72,6 +72,12 @@
 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
@@ -228,8 +234,21 @@ async def load(
                 fqme,
                 timeframe,
             )
-        except FileNotFoundError:
-            return None
+        except FileNotFoundError as fnfe:
+
+            bs_fqme, _, *_ = fqme.rpartition('.')
+
+            possible_matches: list[str] = []
+            for tskey in self._index:
+                if bs_fqme in tskey:
+                    possible_matches.append(tskey)
+
+            match_str: str = '\n'.join(possible_matches)
+            raise TimeseriesNotFound(
+                f'No entry for `{fqme}`?\n'
+                f'Maybe you need a more specific fqme-key like:\n\n'
+                f'{match_str}'
+            ) from fnfe
 
         times = array['time']
         return (
@@ -376,6 +395,8 @@ async def delete_ts(
     #     ...
 
 
+# TODO: does this need to be async on average?
+# I guess for any IPC connected backend yes?
 @acm
 async def get_client(
 
@@ -393,7 +414,7 @@ async def get_client(
     '''
     datadir: Path = config.get_conf_dir() / 'nativedb'
     if not datadir.is_dir():
-        log.info(f'Creating `nativedb` director: {datadir}')
+        log.info(f'Creating `nativedb` dir: {datadir}')
         datadir.mkdir()
 
     client = NativeStorageClient(datadir)