We warmly welcome you to the Friendly King Community's Candy Crush Saga forum.😍
I'm so sorry for your problem. In the case of Android or iphone, your collected booster is stored in phone memory. This stored booster can not be synced with the server, because the game studio still does not have this process. You will not be lose the complete booster for app crashing and the boosters are not refundable.😎
Here are some tips for not/less facing this kind of problem in the future.
Make your device software auto update.
Make your game app auto update.
Don't open game when battery below 25%
Don't accept incoming call when you playing this game.
Close all background running app before start this game.
Make free device internal memory up to 2 GB
Keep RAM free.
