//miniwasm/x/tokenfactory/keeper/before_send.go
func (k Keeper) setBeforeSendHook(ctx context.Context, denom string, cosmwasmAddress string) error {
...
	// delete the store for denom prefix store when cosmwasm address is nil
|>	if cosmwasmAddress == "" {
		return k.DenomHookAddr.Remove(ctx, denom) //@audit empty cosmwasmAddress is used to delete the store
	} else {
		// if a contract is being set, call the contract using cache context
		// to test if the contract is an existing, valid contract.
		cacheCtx, _ := sdk.UnwrapSDKContext(ctx).CacheContext()
//miniwasm/x/tokenfactory/keeper/msg_server.go
func (server msgServer) SetBeforeSendHook(ctx context.Context, msg *types.MsgSetBeforeSendHook) (*types.MsgSetBeforeSendHookResponse, error) {
        //@audit when msg.cosmwasmAddress is empty, Validate will always return error.
|>	if err := msg.Validate(server.ac); err != nil {
		return nil, err
	}
...
//miniwasm/x/tokenfactory/types/msgs.go
func (m MsgSetBeforeSendHook) Validate(accAddrCodec address.Codec) error {
...
	if addr, err := accAddrCodec.StringToBytes(m.CosmwasmAddress); err != nil {
		return err
	} else if len(addr) == 0 {
		return ErrEmptySender
	}
...
