Error(s) in re-building vignettes:
  ...
--- re-building ‘chisq_test.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Quitting from lines 90-98 (chisq_test.Rmd) 
Error: processing vignette 'chisq_test.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘chisq_test.Rmd’

--- re-building ‘flights_examples.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Quitting from lines 69-79 (flights_examples.Rmd) 
Error: processing vignette 'flights_examples.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘flights_examples.Rmd’

--- re-building ‘mtcars_examples.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

--- finished re-building ‘mtcars_examples.Rmd’

--- re-building ‘observed_stat_examples.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Quitting from lines 67-77 (observed_stat_examples.Rmd) 
Error: processing vignette 'observed_stat_examples.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘observed_stat_examples.Rmd’

--- re-building ‘two_sample_t.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Quitting from lines 89-98 (two_sample_t.Rmd) 
Error: processing vignette 'two_sample_t.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘two_sample_t.Rmd’

SUMMARY: processing the following files failed:
  ‘chisq_test.Rmd’ ‘flights_examples.Rmd’ ‘observed_stat_examples.Rmd’
  ‘two_sample_t.Rmd’

Error: Vignette re-building failed.
Execution halted