Error(s) in re-building vignettes:
--- re-building 'Enhancing_Chemical_Data_Access_with_PubChemR.Rmd' using rmarkdown

Quitting from Enhancing_Chemical_Data_Access_with_PubChemR.Rmd:107-109 [unnamed-chunk-9]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<error/rlang_error>
Error in `UseMethod()`:
! no applicable method for 'sectionList' applied to an object of class "NULL"
---
Backtrace:
    ▆
 1. └─PubChemR::sectionList(section)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Error: processing vignette 'Enhancing_Chemical_Data_Access_with_PubChemR.Rmd' failed with diagnostics:
no applicable method for 'sectionList' applied to an object of class "NULL"
--- failed re-building 'Enhancing_Chemical_Data_Access_with_PubChemR.Rmd'

--- re-building 'Exploring_Chemical_Data_with_PubChemR.Rmd' using rmarkdown
--- finished re-building 'Exploring_Chemical_Data_with_PubChemR.Rmd'

--- re-building 'Working_with_PubChemR_to_Access_Chemical_Data.Rmd' using rmarkdown

Quitting from Working_with_PubChemR_to_Access_Chemical_Data.Rmd:882-884 [get_properties_aspirin]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<error/rlang_error>
Error in `retrieve.PubChemInstanceList()`:
! All instances in the object contain NULL results. Please check if the data was retrieved correctly.
---
Backtrace:
    ▆
 1. ├─PubChemR::retrieve(object = props, .which = "aspirin", .to.data.frame = TRUE)
 2. └─PubChemR:::retrieve.PubChemInstanceList(...)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Error: processing vignette 'Working_with_PubChemR_to_Access_Chemical_Data.Rmd' failed with diagnostics:
All instances in the object contain NULL results. Please check if the data was retrieved correctly.
--- failed re-building 'Working_with_PubChemR_to_Access_Chemical_Data.Rmd'

SUMMARY: processing the following files failed:
  'Enhancing_Chemical_Data_Access_with_PubChemR.Rmd'
  'Working_with_PubChemR_to_Access_Chemical_Data.Rmd'

Error: Vignette re-building failed.
Execution halted