Having the error "Error in copy_msts(y, fitted) : x and y should have the same number of observations"

Hi I have current the error:

"Error in copy_msts(y, fitted) : 
 x and y should have the same number of observations"

after running this line of code tsla_train_forecast= rwf(tsla_train, h=6)

Here is my code:

library(forecast)

library(quantmod)
getSymbols("TSLA",from="2022-09-01", to="2023-06-16")
chartSeries(TSLA, multi.col = TRUE, theme = "white")
summary(TSLA)
Tesla=TSLA$TSLA.Close
plot(Tesla)

Teslamf=meanf(Tesla,h=6)
plot(Teslamf)
Teslamf
Teslamf$fitted
Teslamf$residuals
acf(Teslamf$residuals)
checkresiduals(Teslamf)

tsla_train=TSLA[1:189]
tsla_test=TSLA[190:196]
tsla_test$TSLA.Close

tsla_train_forecast= rwf(tsla_train, h=6)
tsla_train_forecast
tsla_test-tsla_train_forecast$mean

I'm not sure what I am doing wrong, it worked fine when I was using AAPL stock data.

The problem is that rwf() is designed for univariate time series, and you are using it with a multivariate time series. Unfortunately, the error message isn't helpful. If you use rwf(tsla_train[,1], h=6), the forecasts are produced without error.

A second issue is that you are using xts objects, but the forecast package is designed to handle ts objects. Mostly, it will convert xts to ts on the fly, but occasionally this could cause an error.