title: Input `var` must be a vector, not a `formula` object. [case_when ; mutate problems]
body: <p>Anyone experienced this problem before? I´m workning with a huge data set and data below is just a sample. I haven´t been able to reproduce the problem by creating a dummy tibble.</p>
  <pre><code>&gt; df
  # A tibble: 5 x 2
    D_INDDTO   D_UDDTO   
    &lt;date&gt;     &lt;date&gt;    
  1 2000-05-12 2000-05-12
  2 2000-05-12 2000-05-12
  3 2000-05-12 2000-05-12
  4 2000-05-12 2000-05-12
  5 2000-05-15 2000-05-22
  
  
  &gt; df%&gt;%mutate(var=case_when(D_INDDTO==D_UDDTO)~&quot;X&quot;)
  
  Error: Problem with `mutate()` input `var`.
  x Input `var` must be a vector, not a `formula` object.
  i Input `var` is `case_when(D_INDDTO == D_UDDTO) ~ &quot;X&quot;`.
  Run `rlang::last_error()` to see where the error occurred.
  
  
  &gt; rlang::last_error()
  &lt;error/dplyr_error&gt;
  Problem with `mutate()` input `var`.
  x Input `var` must be a vector, not a `formula` object.
  i Input `var` is `case_when(D_INDDTO == D_UDDTO) ~ &quot;X&quot;`.
  Backtrace:
    9. dplyr::mutate(., var = case_when(D_INDDTO == D_UDDTO) ~ &quot;X&quot;)
   11. dplyr:::mutate_cols(.data, ...)
   12. base::tryCatch(...)
   13. base:::tryCatchList(expr, classes, parentenv, handlers)
   14. base:::tryCatchOne(expr, names, parentenv, handlers[[1L]])
   15. value[[3L]](cond)
   16. dplyr:::stop_mutate_not_vector(index = i, dots = dots, result = e$result)
   17. dplyr:::stop_dplyr(...)
  Run `rlang::last_trace()` to see the full context.
  &gt; 
  </code></pre>