fix: guard WallTool grid handlers against null wallPreviewRef

[anton-pascal]

Sentry: MONOREPO-EDITOR-BE (issue 7494188332)

TypeError: Cannot set properties of null (setting 'visible') in WallTool.

Root cause

onGridClick is subscribed to the mitt grid:click event. When the user switches tools mid-draft, the WallTool preview <mesh> unmounts and wallPreviewRef.current becomes null — but a queued grid:click event can still fire before the effect cleanup runs emitter.off. The state-1 branch then writes wallPreviewRef.current.visible = false on a null ref and throws.

Fix

Add if (!wallPreviewRef.current) return at the top of onGridClick, mirroring the guard onGridMove already has (if (!(cursorRef.current && wallPreviewRef.current)) return). stopDrafting already null-guards its wallPreviewRef.current.visible write (it's also called from onCancel), so no change needed there.

curve-tool.tsx was checked for the same pattern — its onGridClick doesn't touch a preview mesh ref, so no change needed.

Typecheck (tsc --build in packages/nodes): ✅ passes.

Precedent: same class of fix as "fix: guard onShelfMove against null cursorGroupRef (Sentry EDITOR-BC)".

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Project	Status	Preview	Updated (UTC)
pascal	🔴 Failed	–	Jun 10, 2026, 4:18 AM

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[anton-pascal]

Heads-up for review: this PR overlaps with #371 — both guard wallPreviewRef.current in wall/tool.tsx, created by the nightly Sentry triage on different nights (#371 on 6/04 targets the line-545 write path; this one targets onGridClick entry + stopDrafting). The guards are complementary, not conflicting, but they should be reviewed/merged together — or consolidated into one PR if preferred. Happy to consolidate on request.

[anton-pascal]

Closing: superseded by #397 (merged aab48e0). The onGridClick entry + stopDrafting guards are covered by Aymeric's 04880d4 in the bug-sweep.