tsoutliers save model

Hi guys
Im trying to save a tso model so I can deploy as a webservice.
I want to detect A0 outliers.

Step 1) Convert Data to Timeseries
ts_data<-ts(data$var1, frequency=365, start = data$Date[1])

Step 2) Call tso function and id AO outliers
final_model<-tso(ts_data,types=c("AO"))

Step 3) Save Model
saveRDS(final_model,"./final_model.rds")

However, when I try to use the model on another timeseries dataset i get "Error in tso0(x = y, xreg = xreg, cval = cval, delta = delta, types = types, : trying to get slot "y" from an object (class "tsoutliers") that is not an S4 object"

Has anyone experineced this or knows how to save a tso model properly?
Regards Vincent