Error(s) in re-building vignettes:
  ...
--- re-building ‘learningtower_school.Rmd’ using rmarkdown
** Processing: /home/hornik/tmp/R.check/r-release-gcc/Work/PKGS/learningtower.Rcheck/vign_test/learningtower/vignettes/learningtower_school_files/figure-html/unnamed-chunk-1-1.png
768x576 pixels, 3x8 bits/pixel, RGB
Input IDAT size = 23061 bytes
Input file size = 23163 bytes

Trying:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 20619
  zc = 9  zm = 8  zs = 1  f = 0
  zc = 1  zm = 8  zs = 2  f = 0
  zc = 9  zm = 8  zs = 3  f = 0
  zc = 9  zm = 8  zs = 0  f = 5
  zc = 9  zm = 8  zs = 1  f = 5
  zc = 1  zm = 8  zs = 2  f = 5
  zc = 9  zm = 8  zs = 3  f = 5
                               
Selecting parameters:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 20619

Output IDAT size = 20619 bytes (2442 bytes decrease)
Output file size = 20697 bytes (2466 bytes = 10.65% decrease)

trying URL 'https://github.com/kevinwang09/learningtower/raw/master/student_full_data/student_2018.rds'
Content type 'application/octet-stream' length 9945304 bytes (9.5 MB)
==================================================
downloaded 9.5 MB


Quitting from lines 90-117 [unnamed-chunk-2] (learningtower_school.Rmd)
Error: processing vignette 'learningtower_school.Rmd' failed with diagnostics:
Can't join `x$year` with `y$year` due to incompatible types.
ℹ `x$year` is a <integer>.
ℹ `y$year` is a <factor<cf734>>.
--- failed re-building ‘learningtower_school.Rmd’

--- re-building ‘learningtower_student.Rmd’ using rmarkdown
** Processing: /home/hornik/tmp/R.check/r-release-gcc/Work/PKGS/learningtower.Rcheck/vign_test/learningtower/vignettes/learningtower_student_files/figure-html/unnamed-chunk-2-1.png
768x576 pixels, 3x8 bits/pixel, RGB
Input IDAT size = 22149 bytes
Input file size = 22251 bytes

Trying:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 17795
  zc = 9  zm = 8  zs = 1  f = 0
  zc = 1  zm = 8  zs = 2  f = 0
  zc = 9  zm = 8  zs = 3  f = 0
  zc = 9  zm = 8  zs = 0  f = 5
  zc = 9  zm = 8  zs = 1  f = 5
  zc = 1  zm = 8  zs = 2  f = 5
  zc = 9  zm = 8  zs = 3  f = 5
                               
Selecting parameters:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 17795

Output IDAT size = 17795 bytes (4354 bytes decrease)
Output file size = 17873 bytes (4378 bytes = 19.68% decrease)

trying URL 'https://github.com/kevinwang09/learningtower/raw/master/student_full_data/student_2012.rds'
Content type 'application/octet-stream' length 4996808 bytes (4.8 MB)
==================================================
downloaded 4.8 MB

trying URL 'https://github.com/kevinwang09/learningtower/raw/master/student_full_data/student_2018.rds'
Content type 'application/octet-stream' length 9945304 bytes (9.5 MB)
==================================================
downloaded 9.5 MB

** Processing: /home/hornik/tmp/R.check/r-release-gcc/Work/PKGS/learningtower.Rcheck/vign_test/learningtower/vignettes/learningtower_student_files/figure-html/unnamed-chunk-4-1.png
768x576 pixels, 3x8 bits/pixel, RGB
Input IDAT size = 38263 bytes
Input file size = 38389 bytes

Trying:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 29800
  zc = 9  zm = 8  zs = 1  f = 0
  zc = 1  zm = 8  zs = 2  f = 0
  zc = 9  zm = 8  zs = 3  f = 0
  zc = 9  zm = 8  zs = 0  f = 5
  zc = 9  zm = 8  zs = 1  f = 5
  zc = 1  zm = 8  zs = 2  f = 5
  zc = 9  zm = 8  zs = 3  f = 5
                               
Selecting parameters:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 29800

Output IDAT size = 29800 bytes (8463 bytes decrease)
Output file size = 29878 bytes (8511 bytes = 22.17% decrease)

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

SUMMARY: processing the following file failed:
  ‘learningtower_school.Rmd’

Error: Vignette re-building failed.
Execution halted