This can trigger a crash or incorrect behavior if the sharding components are accessed before being fully initialized.

One example is that the ShardServerCatalogCacheLoader is created in initializeGlobalShardingStateForMongoD before Grid::setShardingInitialized but its ReplicaSetRole member variable is initialized later in initializeShardingEnvironmentOnShardServer after Grid::setShardingInitialized. This can lead to a crash because various methods in the ShardServerCatalogCacheLoader invariant that the ReplicaSetRole will not be ReplicaSetRole::None.

An example is shown here (and the corresponding Evergreen task).