TSL: Improve error message for operators with void values

[sunag]

Related issue: #30849

Description

Improve error message for operators with void values.

material.colorNode = add( 1, Fn( () => {} )() );

New

Old

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	338.63 79.03	338.63 79.03	+0 B +0 B
WebGPU	567.9 157.11	567.91 157.09	+13 B -20 B
WebGPU Nodes	566.51 156.86	566.52 156.84	+13 B -20 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	470.38 113.78	470.38 113.78	+0 B +0 B
WebGPU	641.64 173.58	641.65 173.56	+13 B -18 B
WebGPU Nodes	596.28 162.88	596.3 162.86	+13 B -21 B