Describe the bug

• What I am doing: I am using the create_signed_urls function to generate signed URLs for files in a Supabase storage bucket.
• What I expect is: If a specified file path does not exist in the bucket, I expect the function to gracefully handle the API response (which may return None for the signedURL for that file) without raising a ValidationError.
• What actually happening is: When a file path does not exist, the create_signed_urls function raises a pydantic_core._pydantic_core.ValidationError because the Pydantic model SignedUrlsJsonItem expects a string type for signedURL, but the API returns None (null) in such cases.

Reproduction

When calling create_signed_urls with a list of file paths, if one of the files does not exist, the Supabase API returns a response similar to this:

[
    {
        "error": null,
       "path": "existing_file.txt",
       "signedURL": "/object/sign/fileio/existing_file.txt?token=..."
    },
    {
       "error": "Either the object does not exist or you do not have access to it",
       "path": "non_existent_file.txt",
       "signedURL": null
   }
]

The SignedUrlsJsonResponse in the current SDK is defined using SignedUrlsJsonItem, which currently expects signedURL to be a string:

class SignedUrlsJsonItem(BaseModel, extra="ignore"):
   error: Optional[str]
   path: str
   signedURL: str # This is the problematic field, should be Optional[str]
   
SignedUrlsJsonResponse = TypeAdapter(list[SignedUrlsJsonItem])

Because the SDK definition requires signedURL to be a string, it fails validation when it receives null from the API, leading to the

pydantic_core._pydantic_core.ValidationError: 1 validation error for list[SignedUrlsJsonItem] 1.signedURL Input should be a valid string [type=string_type, input_value=None, input_type=NoneType]

Here's an example of how to trigger this (assuming non_existent_file.txt does not exist):

# Assuming you have a client and bucket initialized
# from supabase import create_client, Client

# url: str = "YOUR_SUPABASE_URL"
# key: str = "YOUR_SUPABASE_ANON_KEY"
# supabase: Client = create_client(url, key)
# bucket_name = "your-bucket-name"

# Example call that might trigger the error if 'non_existent_file.txt' does not exist
# The actual error occurs within the SDK's internal processing of the API response.
try:
   # Example: a list of file paths, where one or more might not exist
   paths_to_sign = ["existing_file.txt", "non_existent_file.txt"]
   expires_in_seconds = 3600
   
   # This call would fail if 'non_existent_file.txt' does not exist
   signed_urls = supabase.storage.from_(bucket_name).create_signed_urls(
       paths_to_sign, expires_in_seconds
   )
   print(signed_urls)
except Exception as e:
   print(f"An error occurred: {e}")
   # Expected to catch pydantic_core._pydantic_core.ValidationError

Steps to reproduce

No response

Library affected

storage3

Library version

supabase 2.28.3

Python version

Python 3.13.12