fix(fs): handle folder info array response

[syscc]

Summary

This fixes the root cause behind OpenListTeam/OpenList#2562.

The 115 Open /open/folder/get_info API may return data as an array for path-based folder info lookups, especially when the requested path is missing. The SDK currently always unmarshals data into GetFolderInfoResp, so callers receive:

json: cannot unmarshal array into Go value of type sdk.GetFolderInfoResp

This change makes GetFolderInfoResp accept both shapes:

• object: existing behavior
• non-empty array: use the first item
• empty array: return ErrObjectNotFound

This allows callers such as OpenList to distinguish missing objects from real JSON/schema failures.

Related

• OpenList issue: [BUG] 115 网盘开放平台新建文件夹报错 OpenList#2562
• OpenList PR discussion: fix(115-open): handle missing path info OpenList#2563

Testing

• gofmt -w fs.go error.go fs_test.go
• git diff --check

I did not run go test locally because the downstream OpenList task is under a local testing constraint that forbids generating compiled test artifacts/caches.

AI Disclosure

This PR includes AI-assisted content.

Tools used:

• OpenAI Codex

Usage scope:

• Code generation
• Test drafting
• PR description drafting

I reviewed and validated the AI-assisted content before submission. The commit includes Co-authored-by: OpenAI Codex <codex@openai.com> attribution.

[Copilot]

Pull request overview

This PR fixes GetFolderInfo / GetFolderInfoByPath decoding when the 115 /open/folder/get_info API returns data as an array (notably for missing path lookups), enabling callers to reliably detect “not found” vs. true JSON/schema errors.

Changes:

• Added a custom UnmarshalJSON to GetFolderInfoResp to accept both object and array data shapes, mapping an empty array to ErrObjectNotFound.
• Introduced ErrObjectNotFound as a package-level sentinel error for missing objects.
• Added unit tests covering object, array, and empty-array unmarshalling for GetFolderInfoResp.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
fs.go	Implements tolerant JSON unmarshalling for folder info responses that may be object or array.
error.go	Adds a reusable ErrObjectNotFound sentinel error.
fs_test.go	Adds tests validating the new unmarshalling behavior, including the empty-array not-found case.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[xrgzs]

LGTM

[SheltonZhu]

LGTM