installing fgeo.biomass error: https://forestgeo.github.io/drat/ not found

[ValentineHerr]

@maurolepore , in the DESCRIPTION file, there is:

Additional_repositories: https://forestgeo.github.io/drat/

But that website does not exist (any more?)

Can you explain why that line is there and if it is safe to delete it?
Currently the command

devtools::install_github("forestgeo/fgeo.biomass")

gives an error:

> devtools::install_github("forestgeo/fgeo.biomass")
Downloading GitHub repo forestgeo/fgeo.biomass@master
These packages have more recent versions available.
Which would you like to update?

 1: All                              
 2: CRAN packages only               
 3: None                             
 4: usethis (1.5.0  -> 1.5.1 ) [CRAN]
 5: raster  (2.9-5  -> 3.0-2 ) [CRAN]
 6: Rcpp    (1.0.1  -> 1.0.2 ) [CRAN]
 7: digest  (0.6.19 -> 0.6.20) [CRAN]
 8: hms     (0.5.0  -> 0.5.1 ) [CRAN]
 9: clipr   (0.6.0  -> 0.7.0 ) [CRAN]
10: curl    (3.3    -> 4.1   ) [CRAN]
11: whisker (0.3-2  -> 0.4   ) [CRAN]
12: httr    (1.4.0  -> 1.4.1 ) [CRAN]
13: openssl (1.4    -> 1.4.1 ) [CRAN]
14: sys     (3.2    -> 3.3   ) [CRAN]

Enter one or more numbers, or an empty line to skip updates:

Installing 6 packages: BIOMASS, fgeo.tool, formatR, measurements, minpack.lm, rappdirs
Installing packages into ‘C:/Users/HerrmannV/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
Error: Failed to install 'fgeo.biomass' from GitHub:
  (converted from warning) unable to access index for repository https://forestgeo.github.io/drat/src/contrib:
  cannot open URL 'https://forestgeo.github.io/drat/src/contrib/PACKAGES'
In addition: Warning messages:
1: In untar2(tarfile, files, list, exdir) :
  skipping pax global extended headers
2: In untar2(tarfile, files, list, exdir) :
  skipping pax global extended headers
> sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 14393)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                           LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.1        ps_1.3.0          prettyunits_1.0.2 rprojroot_1.3-2   withr_2.1.2       digest_0.6.19    
 [7] crayon_1.3.4      assertthat_0.2.1  R6_2.4.0          backports_1.1.4   magrittr_1.5      rlang_0.4.0      
[13] cli_1.1.0         curl_3.3          fs_1.3.1          remotes_2.1.0     rstudioapi_0.10   callr_3.2.0      
[19] desc_1.2.0        devtools_2.0.2    tools_3.6.0       glue_1.3.1        pkgload_1.0.2     compiler_3.6.0   
[25] processx_3.3.1    pkgbuild_1.0.3    sessioninfo_1.1.1 memoise_1.1.0     usethis_1.5.0 

[maurolepore]

It should be okay to remove that line.

The ‘Additional_repositories’ field is a comma-separated list of repository URLs where
the packages named in the other fields may be found. It is currently used by R CMD check to
check that the packages can be found, at least as source packages (which can be installed on any
platform).
--- https://cran.r-project.org/doc/manuals/r-release/R-exts.pdf