Falling particles from a modding falling block (such as custom sand) with a color provider will have `null` passed in world and pos when calculating the color of the particle. Therefore, the world and pos context are not useable in a color provider when calculating the particle color.

Code Analysis

(Yarn mappings)

`null` is passed in to `BlockColorProvider.getColor` in `BlockColors.getParticleColor`.

Potential Solution

Replace the two `null` on line 111 with `world` and `pos`.