refactor: not to raise exceptions or warnings

Signed-off-by: ktro2828 <kotaro.uetake@tier4.jp>

Author: ktro2828

t4_devkit/tier4.py

@@ -86,14 +86,9 @@ def load_metadata(db_root: str, revision: str | None = None) -> DBMetadata:
             version = None
             data_root = db_root_path.as_posix()
     else:
-        if int(revision) not in version_candidates:
-            raise ValueError(f"The version: {revision} is not included in {dataset_id}")
         version = revision
         data_root = db_root_path.joinpath(version).as_posix()
 
-    if version is None:
-        warnings.warn(f"{dataset_id} does't contain any versions.", DeprecationWarning)
-
     return DBMetadata(data_root=data_root, dataset_id=dataset_id, version=version)
 
 
@@ -149,6 +144,11 @@ def __init__(
         if not osp.exists(self.data_root):
             raise FileNotFoundError(f"Database directory is not found: {self.data_root}")
 
+        if self.version is None:
+            warnings.warn(
+                f"DatasetID: {self.dataset_id} does't contain any versions.", DeprecationWarning
+            )
+
         start_time = time.time()
         if verbose:
             print(f"======\nLoading T4 tables in `{self.schema_dir}`...")