Here is the error:

|.................... | 39% [unnamed-chunk-5] Error in is.nan():
! default method not implemented for type 'list'
Backtrace:

1. JointAI::lme_imp(...)
2. JointAI (local) <fn>(...)
3. JointAI:::check_data(data, fixed, random, auxvars, timevar, mess)
4. JointAI:::convert_variables(...)
5. tibble:::[<-.tbl_df(*tmp*, is.nan(data[, k]), k, value = <lgl>)

Here is the code: lmimp1<- lme_imp(phqtotal~time_25 + treat + treat:time_25 + PHQBL + time_25:PHQBL+nonwhite +(1|id)
+(1|cohort), data =rostlong1r)

Here is the result of lapply for my dataset:

View(rostlong1r)
lapply(rostlong1r, class)
$id
[1] "numeric"

$phqtotal
[1] "numeric"

$time_25
[1] "numeric"

$treat
[1] "numeric"

$PHQBL
[1] "numeric"

$nonwhite
[1] "numeric"

$cohort
[1] "numeric"