Hi gang.
https://www.babylonjs-playground.com/#UP2O8#44
That WAS a "sparkly particles" playground... via custom update function.
Activate line 132... to activate custom update function. Fails.
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Maybe a better proof-case:
https://playground.babylonjs.com/#U4QCE#5
Line 5 -> myUpdate() function... return BABYLON.ParticleSystem._update(newParticles); (the default action, right?)
Now activate the function... activate line 80. Poom! 
DOA. Ideas? (thx)
Could be Wingnut mistake, though. Usually is.
But I am seeing BJS-wide "sparticles" (sparkly particles) failure in all playgrounds, at this time. (oh no). They all require custom update funcs.
Maybe work is in-progress, by somebody. Cool. Dev is good.