Commands that are only supported on sharded clusters are typically gated by a call to assertCanAcceptShardedCommands(), which fails with a clear ShardingStateNotInitialized error when the command is invoked on a replica set (i.e. a node that isn't part of a sharded cluster).

The autoSplitVector command does not follow this pattern. Its typedRun performs its own uassert check on ClusterRole::ShardServer (auto_split_vector_command.cpp#L97-L99) before reaching the assertCanAcceptShardedCommands() call. As a result, invoking autoSplitVector on a replica set fails with:

IllegalOperation: The autoSplitVector command can only be invoked on shards (no CSRS).

instead of the standard ShardingStateNotInitialized error other shard-only commands produce. This inconsistency is confusing for callers/operators, since the message references "shards" and "CSRS" rather than indicating that the node simply isn't part of a sharded cluster.

We should make autoSplitVector's error behavior consistent with other shard-only commands by relying on assertCanAcceptShardedCommands() instead of (or before) the separate ClusterRole check.