According to http://uproxx.com/hitfix/star-wars-last-jedi-crait/2/ Crait is a salt planet:
If you’re not sure what Crait is, you’re not alone. The name was exclusively revealed to Entertainment Weekly by director Rian Johnson. But we’ve all seen the planet. Think back to the trailer that was released at Star Wars Celebration Orlando 2017. In one sequence, a line of Resistance ships speed across a salt flat, kicking up blood red dust in their wake as they head into battle against distant First Order variations of AT-ATs. That desert is on Crait.
Just because LEGO didn't get the memo about Crait being a salt planet, and assuming: white = snow, so the FO troopers must be Snowtroopers, doesn't suddenly turn Crait into a snow planet.