fix: Fix transparent blocks render issue on non-Chrome browsers

[FlySkyPie]

The transparent block also can't render on Firefox, and I saw this warning from console:

WebGL warning: drawElementsInstanced: Indexed vertex fetch requires 1872 vertices, but attribs only supply 1024.

Seems t_geometry.setIndex using indeies over size of t_positions.

Although I already refactoring this project with modern web tools, but I think I should share this fix, thanks for open source this awesome project. :)