Ensure default supported_versions is a tuple, as in type (#4348)

Author: alejoe91

src/spikeinterface/curation/curation_model.py

@@ -1,4 +1,4 @@
-from pydantic import BaseModel, Field, model_validator, field_validator
+from pydantic import BaseModel, Field, model_validator, field_validator, field_serializer
 from typing import List, Dict, Union, Optional, Literal, Tuple
 from itertools import chain, combinations
 import numpy as np
@@ -77,7 +77,7 @@ def get_full_spike_indices(self, sorting: BaseSorting):
 
 class CurationModel(BaseModel):
     supported_versions: Tuple[Literal["1"], Literal["2"]] = Field(
-        default=["1", "2"], description="Supported versions of the curation format"
+        default=("1", "2"), description="Supported versions of the curation format"
     )
     format_version: str = Field(description="Version of the curation format")
     unit_ids: List[Union[int, str]] = Field(description="List of unit IDs")
@@ -238,11 +238,11 @@ def check_splits(cls, values):
         for i, split in enumerate(splits):
             if isinstance(split, dict):
                 split = dict(split)
-                if "indices" in split:
+                if "indices" in split and split["indices"] is not None:
                     split["indices"] = [list(indices) for indices in split["indices"]]
-                if "labels" in split:
+                if "labels" in split and split["labels"] is not None:
                     split["labels"] = list(split["labels"])
-                if "new_unit_ids" in split:
+                if "new_unit_ids" in split and split["new_unit_ids"] is not None:
                     split["new_unit_ids"] = list(split["new_unit_ids"])
                 splits[i] = Split(**split)