LockedBuffer.Copy() crashes with access violation on Windows when buffer is valid and alive

[xMinhx]

Describe the bug Calling (*memguard.LockedBuffer).Copy() results in a fatal access violation on Windows, even though the buffer is non-nil, alive (IsAlive() returns true), and accessed under a sync.RWMutex that guards against concurrent Destroy() or Swap().

Replacing .Copy() with copy(out, buf.Bytes()) avoids the issue.

To Reproduce Steps to reproduce the behavior:

Create a LockedBuffer using memguard.NewBufferFromBytes Call .Copy() into equally sized destination buffer

-> panic or access violation

buf := memguard.NewBufferFromBytes([]byte("test"))
defer buf.Destroy()

out := make([]byte, buf.Size())
buf.Copy(out)

Expected behaviour Copy() should copy memory from a valid, non-destroyed buffer. It should not crash when:

• The buffer is alive
• The buffer size is non-zero

System: OS and Kernel Versions: Microsoft Windows [Version 10.0.26100.3775] Memguard Version: v0.22.5 Go Version: go1.24.1 (Windows amd64)

Additional context

• Tried with Mutex
• No concurrent calls to .Destroy() or .Swap()
• .IsAlive() returns true before .Copy()
• .Bytes() works fine under same locking conditions
• Switching to append([]byte(nil), buf.Bytes()...) avoids crash completely.