Fix missing flat ids

Author: Nikos Papailiou

apis/python/src/tiledb/vector_search/flat_index.py

@@ -36,12 +36,15 @@ def __init__(
             ctx=self.ctx,
             config=config,
         )
-        self.ids_uri = self.group[
-            storage_formats[self.storage_version]["IDS_ARRAY_NAME"] + self.index_version
-        ].uri
-        if tiledb.array_exists(self.ids_uri, self.ctx):
-            self._ids = read_vector_u64(self.ctx, self.ids_uri, 0, 0)
-        else:
+        try:
+            self.ids_uri = self.group[
+                storage_formats[self.storage_version]["IDS_ARRAY_NAME"] + self.index_version
+            ].uri
+            if tiledb.array_exists(self.ids_uri, self.ctx):
+                self._ids = read_vector_u64(self.ctx, self.ids_uri, 0, 0)
+            else:
+                self._ids = StdVector_u64(np.arange(self.size).astype(np.uint64))
+        except tiledb.TileDBError:
             self._ids = StdVector_u64(np.arange(self.size).astype(np.uint64))
 
         dtype = self.group.meta.get("dtype", None)