only update tx rate limit *after* ensure

Author: camfairchild

pallets/subtensor/src/staking/set_children.rs

@@ -59,15 +59,6 @@ impl<T: Config> Pallet<T> {
             Error::<T>::TxRateLimitExceeded
         );
 
-        // Set last transaction block
-        let current_block = Self::get_current_block_as_u64();
-        Self::set_last_transaction_block_on_subnet(
-            &hotkey,
-            netuid,
-            &TransactionType::SetChildren,
-            current_block,
-        );
-
         // Check that this delegation is not on the root network. Child hotkeys are not valid on root.
         ensure!(
             netuid != Self::get_root_netuid(),
@@ -119,6 +110,15 @@ impl<T: Config> Pallet<T> {
             Error::<T>::NotEnoughStakeToSetChildkeys
         );
 
+        // Set last transaction block
+        let current_block = Self::get_current_block_as_u64();
+        Self::set_last_transaction_block_on_subnet(
+            &hotkey,
+            netuid,
+            &TransactionType::SetChildren,
+            current_block,
+        );
+
         // Calculate cool-down block
         let cooldown_block =
             Self::get_current_block_as_u64().saturating_add(DefaultPendingCooldown::<T>::get());