Reconciliation raises an unexpected error

First, this has nothing to do with the hts package. You are using the forecast reconcilation procedures in the fabletools package.

Second, your example consists of a single time series (the ACT), so the reconciliation is degenerate.

Third, SNAIVE is already reconciled since the forecasts are equal to the last year of data, so the reconciliation is degenerate.

That said, we should improve fabletools to prevent the error. @mitchelloharawild

To see it working on a small non-degenerate example, try this:

library(dplyr  , quietly = TRUE)
library(tsibble, quietly = TRUE)
library(fable  , quietly = TRUE)

tsibble::tourism %>%
  filter(State == 'ACT') %>% 
  aggregate_key(State / Region, Trips = sum(Trips)) %>% 
  model(base = fable::SNAIVE(Trips)) %>%
  reconcile(mint_cov = min_trace(base, method = "mint_cov")) %>% 
  forecast(h = 1)

From https://github.com/earowang/hts/issues/43#issuecomment-1139303691

Start by reproducing the reconciliation example in the issue with R, fable, tsibble, and fabletools, then inspect the reconciliation and forecasting path that produces the unexpected error. Done means the non-degenerate example runs without that error and a regression check covers the case; no source file or test is named in the issue.