verb-group_by.md
In dbplyr: A 'dplyr' Back End for Databases

errors for .drop = FALSE

Code
  lazy_frame(x = 1:3, y = 1:3) %>% group_by(y, .drop = FALSE)
Condition
  Error in `group_by()`:
  ! `.drop = FALSE` isn't supported on database backends.
  i It must be TRUE instead.

informative errors for missing variables

Code
  (expect_error(lazy_frame(x = 1:3) %>% group_by(y)))
Output
  <error/rlang_error>
  Error in `group_by()`:
  i In argument: `y`
  Caused by error:
  ! Object `y` not found.

group_by() produces nice error messages

Code
  lf %>% group_by(z = non_existent + 1)
Condition
  Error in `group_by()`:
  i In argument: `z = non_existent + 1`
  Caused by error:
  ! Object `non_existent` not found.
Code
  lf %>% group_by(across(non_existent))
Condition
  Error in `group_by()`:
  i In argument: `across(non_existent)`
  Caused by error in `across()`:
  ! Can't subset columns that don't exist.
  x Column `non_existent` doesn't exist.

ungroup() produces nice error messages

Code
  lazy_frame(x = 1) %>% ungroup(non_existent)
Condition
  Error in `ungroup()`:
  ! Can't subset columns that don't exist.
  x Column `non_existent` doesn't exist.