fix(nodes): guard previewRef in fence tool onGridClick (Sentry EDITOR-BE/CR)

[anton-pascal]

Summary

Fixes a production null-deref crash in the fence tool.

Sentry: MONOREPO-EDITOR-BE / EDITOR-CR
Error: TypeError: Cannot set properties of null (setting 'visible')
Where: editor.pascal.app/editor/:projectId

Root cause

In packages/nodes/src/fence/tool.tsx, the onGridClick handler sets previewRef.current.visible = true / = false without a null guard. previewRef is declared useRef<Mesh>(null!) and is genuinely null until the <mesh ref={previewRef}> mounts. A grid click processed before the preview mesh mounts (or during an unmount race) dereferences null and throws.

The sibling onGridMove handler already guards correctly with if (!(cursorRef.current && previewRef.current)) return.

Fix

Add an early guard at the top of the onGridClick callback, mirroring the existing onGridMove pattern:

const onGridClick = (event: GridEvent) => {
  if (!previewRef.current) return
  ...
}

Minimal and surgical — no other behavior changes.

Testing

Isolated tsc on the package surfaces only pre-existing, unrelated peer-dependency errors (e.g. @pascal-app/viewer exports) that exist on main independent of this change; nothing new is introduced by the one-line guard.

---

Note

Low Risk
Single defensive null check in editor fence drafting; no auth, data, or behavior change when the preview mesh is mounted.

Overview
Adds an early if (!previewRef.current) return at the start of the fence tool’s onGridClick handler so grid clicks are ignored until the preview mesh ref is attached.

This aligns onGridClick with onGridMove, which already bails when previewRef is unset, and prevents production crashes from setting visible on a null ref when a click races mount/unmount.

^{Reviewed by Cursor Bugbot for commit 3e1b830. Bugbot is set up for automated code reviews on this repo. Configure here.}

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Project	Status	Preview	Updated (UTC)
pascal	🔴 Failed	–	Jun 21, 2026, 4:07 AM

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