TSL: Fix instance() optional parameter

[sunag]

Related issue: #30783

Description

Fix instance() optional parameter.

[Copilot]

Pull Request Overview

This PR fixes the instance() function by making the instanceColor parameter optional, while updating both the documentation and the parameter count settings accordingly.

• Constructor now sets a default value (null) for the instanceColor parameter.
• Documentation annotations have been updated to indicate its optional status.
• The parameter length configuration has been revised using setParameterLength.

Comments suppressed due to low confidence (1)

src/nodes/accessors/InstanceNode.js:224

• Ensure that setParameterLength(2, 3) accurately reflects the intended parameter requirements after making instanceColor optional, and that this change preserves backwards compatibility.

export const instance = /*@__PURE__*/ nodeProxy( InstanceNode ).setParameterLength( 2, 3 );

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.36 78.34	336.36 78.34	+0 B +0 B
WebGPU	533.1 148.16	533.08 148.15	-17 B -6 B
WebGPU Nodes	532.56 148.06	532.54 148.05	-17 B -6 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	465.37 112.21	465.37 112.21	+0 B +0 B
WebGPU	604.71 164.13	604.69 164.12	-19 B -10 B
WebGPU Nodes	559.7 153.56	559.68 153.56	-19 B -5 B

[sunag]

/cc @brunosimon