- What I did

Fixed a missing error check in ContainerTop on Windows that could cause a nil pointer panic.

- How I did it

Added an if err != nil check after the IIFE that acquires the running task under lock in daemon/top_windows.go. Previously, if GetRunningTask() failed (e.g., container not running) or the container was in a restarting state, the error was silently dropped and task.Summary() was called on a nil task, resulting in a panic.

- How to verify it

1. Run docker top against a stopped or restarting Windows container.
2. Before this fix: nil pointer panic.
3. After this fix: a proper error message is returned.

This matches the existing error handling pattern in daemon/top_unix.go.

- Human readable description for the release notes

Fix a panic when running `docker top` on a non-running Windows container.