How can I unnest a listcolumn of tsibbles?

Question

I do not understand how I can unnest a listcolumn of tsibbles. I recently updated the R version of an old project, which caused non working code.

Example data:

library(tidyverse)
library(fable)
library(tsibble)
library(tsibbledata)

data <- tsibbledata::hh_budget
data

# A tsibble: 88 x 8 [1Y]
# Key:       Country [4]
   Country    Year  Debt     DI Expenditure Savings Wealth Unemployment
   <chr>     <dbl> <dbl>  <dbl>       <dbl>   <dbl>  <dbl>        <dbl>
 1 Australia  1995  95.7 3.72          3.40   5.24    315.         8.47
 2 Australia  1996  99.5 3.98          2.97   6.47    315.         8.51
 3 Australia  1997 108.  2.52          4.95   3.74    323.         8.36
 4 Australia  1998 115.  4.02          5.73   1.29    339.         7.68
 5 Australia  1999 121.  3.84          4.26   0.638   354.         6.87
 6 Australia  2000 126.  3.77          3.18   1.99    350.         6.29
 7 Australia  2001 132.  4.36          3.10   3.24    348.         6.74
 8 Australia  2002 149.  0.0218        4.03  -1.15    349.         6.37
 9 Australia  2003 159.  6.06          5.04  -0.413   360.         5.93
10 Australia  2004 170.  5.53          4.54   0.657   379.         5.40
# ... with 78 more rows

nest the data:

data_nested <- data %>% 
               nest(data = c(-Country)) 
 

This would also do the same nesting:

data_nested <- data %>% 
               group_by_key() %>% 
               nest() 

data_nested

Results in this:

# A tibble: 4 x 2
# Groups:   Country [4]
  Country   data              
  <chr>     <list>            
1 Australia <tsibble [22 x 7]>
2 Canada    <tsibble [22 x 7]>
3 Japan     <tsibble [22 x 7]>
4 USA       <tsibble [22 x 7]> 

Now I'd like to unnest this, I would like to get the same as the input data, a tsibble with 88 rows, Key: Country[4],...

Back then I used this:

tsibble::unnest_tsibble(data_nested, cols = data)

Produces an Error Message I do not understand at all.

Error in if (unknown_interval(interval) && (nrows > vec_size(key_data))) { : 
  missing value where TRUE/FALSE needed
In addition: Warning messages:
1: In min(..., na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
2: In max(..., na.rm = TRUE) :
  no non-missing arguments to max; returning -Inf

I know there were these updates, I played a bit around with unnest_wider and unnest_longer and unnest_legacy.

unnest_longer(data_nested, col = data)

Error in if (unknown_interval(interval) && (nrows > vec_size(key_data))) { : 
  missing value where TRUE/FALSE needed
In addition: Warning messages:
1: In min(..., na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
2: In max(..., na.rm = TRUE) :
  no non-missing arguments to max; returning -Inf

Unnest legacy only allows tibbles...

unnest_legacy(data_nested)

Error: The result is not a valid tsibble.
i Do you need `as_tibble()` to work with data frame?

The only thing that worked is really cumbersome:

data_again_unnested <- data_nested %>% 
                       unnest_wider(data) %>% 
                       unnest(cols = c(-Country))
data_again_unnested

# A tibble: 88 x 8
   Country    Year  Debt     DI Expenditure Savings Wealth Unemployment
   <chr>     <dbl> <dbl>  <dbl>       <dbl>   <dbl>  <dbl>        <dbl>
 1 Australia  1995  95.7 3.72          3.40   5.24    315.         8.47
 2 Australia  1996  99.5 3.98          2.97   6.47    315.         8.51
 3 Australia  1997 108.  2.52          4.95   3.74    323.         8.36
 4 Australia  1998 115.  4.02          5.73   1.29    339.         7.68
 5 Australia  1999 121.  3.84          4.26   0.638   354.         6.87
 6 Australia  2000 126.  3.77          3.18   1.99    350.         6.29
 7 Australia  2001 132.  4.36          3.10   3.24    348.         6.74
 8 Australia  2002 149.  0.0218        4.03  -1.15    349.         6.37
 9 Australia  2003 159.  6.06          5.04  -0.413   360.         5.93
10 Australia  2004 170.  5.53          4.54   0.657   379.         5.40
# ... with 78 more rows

But it outputs of course a tibble so I'd would again need to coerce it back to a tsibble, this is quite annoying, a lot of steps, just for a simple unnest.

data_again_unnested %>% as_tsibble(key = Country, index = Year)

# A tsibble: 88 x 8 [1Y]
# Key:       Country [4]
   Country    Year  Debt     DI Expenditure Savings Wealth Unemployment
   <chr>     <dbl> <dbl>  <dbl>       <dbl>   <dbl>  <dbl>        <dbl>
 1 Australia  1995  95.7 3.72          3.40   5.24    315.         8.47
 2 Australia  1996  99.5 3.98          2.97   6.47    315.         8.51
 3 Australia  1997 108.  2.52          4.95   3.74    323.         8.36
 4 Australia  1998 115.  4.02          5.73   1.29    339.         7.68
 5 Australia  1999 121.  3.84          4.26   0.638   354.         6.87
 6 Australia  2000 126.  3.77          3.18   1.99    350.         6.29
 7 Australia  2001 132.  4.36          3.10   3.24    348.         6.74
 8 Australia  2002 149.  0.0218        4.03  -1.15    349.         6.37
 9 Australia  2003 159.  6.06          5.04  -0.413   360.         5.93
10 Australia  2004 170.  5.53          4.54   0.657   379.         5.40
# ... with 78 more rows

Is there no other way to do it? Has anyone an idea?