Running examples in ‘GSIF-Ex.R’ failed
The error most likely occurred in:

> ### Name: SoilGrids-class
> ### Title: A class for SoilGrids - soil property and/or class maps
> ### Aliases: SoilGrids-class SoilGrids
> ### Keywords: classes
> 
> ### ** Examples
> 
> # load soil samples from the plotKML package: 
> library(plotKML)
plotKML version 0.6-1 (2020-03-08)
URL: http://plotkml.r-forge.r-project.org/
> library(aqp)
This is aqp 1.19

Attaching package: ‘aqp’

The following object is masked from ‘package:base’:

    union

> library(plyr)
> library(splines)
> library(rgdal)
Loading required package: sp
rgdal: version: 1.5-15, (SVN revision 1045)
Geospatial Data Abstraction Library extensions to R successfully loaded
Loaded GDAL runtime: GDAL 2.2.4, released 2018/03/19
Path to GDAL shared files: /usr/local/share/gdal
GDAL binary built with GEOS: TRUE 
Loaded PROJ runtime: Rel. 5.2.0, September 15th, 2018, [PJ_VERSION: 520]
Path to PROJ shared files: (autodetected)
Linking to sp version:1.4-2
> library(raster)

Attaching package: ‘raster’

The following objects are masked from ‘package:aqp’:

    metadata, metadata<-

> 
> data(eberg)
> ## subset data to 10%:
> eberg <- eberg[runif(nrow(eberg)) < .1,]
> ## sites table:
> s.lst <- c("ID", "soiltype", "TAXGRSC", "X", "Y")
> h.lst <- c("UHDICM","LHDICM","SNDMHT","SLTMHT","CLYMHT")
> sites <- eberg[,s.lst]
> ## get horizons table:
> horizons <- getHorizons(eberg, idcol="ID", sel=h.lst)
> ## create object of type "SoilProfileCollection"
> eberg.spc <- join(horizons, sites, type='inner')
Joining by: ID
> depths(eberg.spc) <- ID ~ UHDICM + LHDICM
Warning: converting IDs from factor to character
> site(eberg.spc) <- as.formula(paste("~", paste(s.lst[-1], collapse="+"), sep=""))
> coordinates(eberg.spc) <- ~X+Y
> proj4string(eberg.spc) <- CRS("+init=epsg:31467")
> ## convert to logits:
> eberg.spc@horizons$SNDMHT.t <- log((eberg.spc@horizons$SNDMHT/100)/
+     (1-eberg.spc@horizons$SNDMHT/100))
> ## convert to geosamples:
> eberg.geo <- as.geosamples(eberg.spc)
Reprojecting to +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 ...
Warning in wkt(obj) : CRS object has no comment
Warning in wkt(CRS(tg)) : CRS object has no comment
Error in project(t(bbox(obj))[, 1:2], tg, inv = TRUE, use_aoi = FALSE) : 
  is.character(proj) is not TRUE
Calls: as.geosamples ... spTransform -> spTransform -> get_aoi -> project -> stopifnot
Execution halted