Error building vignettes on install from github

[sx57]

Hi - I'm experiencing a fatal error when the gmwm package is being installed with the build_vignettes parameter set to True. The error seems to stem from at least one of the R markdown files Loading-and-Modeling-IMUs.Rmd not being able to find the function is.whole.

See the basic output from the install command below.

Please ask if you need more output or testing. Installing from Rstudio version 1.2.1335, R version 3.6.1. Installation works fine with build_vignettes is set to False, as well.

> devtools::install_github('SMAC-Group/gmwm',build_vignettes = T)
Downloading GitHub repo SMAC-Group/gmwm@master
√  checking for file 'SMAC-Group-gmwm-9336b57/DESCRIPTION' (419ms)
-  preparing 'gmwm': (4s)
√  checking DESCRIPTION meta-information ... 
-  cleaning src
-  installing the package to build vignettes (3.4s)
E  creating vignettes (6m 13.2s)
   --- re-building 'Loading-and-Modeling-IMUs.Rmd' using rmarkdown
   Loading required package: ggplot2
   Loading required package: imudata
   
   Attaching package: 'imudata'
   
   The following objects are masked from 'package:gmwm':
   
       create_imu, imu, read.imu
   
   Quitting from lines 40-45 (Loading-and-Modeling-IMUs.Rmd) 
   Error: processing vignette 'Loading-and-Modeling-IMUs.Rmd' failed with diagnostics:
   could not find function "is.whole"
   --- failed re-building 'Loading-and-Modeling-IMUs.Rmd'
   
   --- re-building 'Manipulating-gmwm-Object-Types.Rmd' using rmarkdown
   --- finished re-building 'Manipulating-gmwm-Object-Types.Rmd'
   
   --- re-building 'Process-to-Haar-Wavelet-Variance-Formulae.Rmd' using rmarkdown
   --- finished re-building 'Process-to-Haar-Wavelet-Variance-Formulae.Rmd'
   
   --- re-building 'Quick-Start-Guide.Rmd' using rmarkdown
   --- finished re-building 'Quick-Start-Guide.Rmd'
   
   SUMMARY: processing the following file failed:
     'Loading-and-Modeling-IMUs.Rmd'
   
   Error: Vignette re-building failed.
   Execution halted
Error: Failed to install 'gmwm' from GitHub:
  System command error, exit status: 1, stdout + stderr (last 10 lines):
E> --- finished re-building 'Process-to-Haar-Wavelet-Variance-Formulae.Rmd'
E> 
E> --- re-building 'Quick-Start-Guide.Rmd' using rmarkdown
E> --- finished re-building 'Quick-Start-Guide.Rmd'
E> 
E> SUMMARY: processing the following file failed:
E>   'Loading-and-Modeling-IMUs.Rmd'
E> 
E> Error: Vignette re-building failed.
E> Execution halted