theme.md
In pkgdown: Make Static HTML Documentation for a Package

check_bslib_theme() works

Code
  check_bslib_theme("paper", pkg, bs_version = 4)
Condition
  Error:
  x In _pkgdown.yml, template.bootswatch contains unknown Bootswatch/bslib theme "paper".
  i Using Bootstrap version 4 (template.bootstrap).

validations yaml specification

Code
  build_bslib_(theme = 1)
Condition
  Error in `bs_theme_rules()`:
  ! In _pkgdown.yml, template.theme must be a string, not the number 1.
Code
  build_bslib_(theme = "fruit")
Condition
  Error in `build_bslib_()`:
  ! In _pkgdown.yml, template.theme uses theme "fruit"
Code
  build_bslib_(`theme-dark` = "fruit")
Condition
  Error in `build_bslib_()`:
  ! In _pkgdown.yml, template.theme-dark uses theme "fruit"