make shure R CMD check does not error

I only have quite minor errors:
Setting env vars --------------------------------------------------------------
CFLAGS  : -Wall -pedantic
CXXFLAGS: -Wall -pedantic
Building opensensmapr ---------------------------------------------------------
'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \
  CMD build '/home/daniel/git/o2r/opensensmapR' --no-resave-data --no-manual 

* checking for file ‘/home/daniel/git/o2r/opensensmapR/DESCRIPTION’ ... OK
* preparing ‘opensensmapr’:
* checking DESCRIPTION meta-information ... OK
* installing the package to build vignettes
* creating vignettes ... OK
Warning: ‘inst/doc’ files
    ‘osem-intro.Rmd’, ‘osem-intro.html’, ‘osem-intro.R’
  ignored as vignettes have been rebuilt.
  Run R CMD build with --no-build-vignettes to prevent rebuilding.
* checking for LF line-endings in source and make files and shell scripts
* checking for empty or unneeded directories
Removed empty directory ‘opensensmapr/tools’
* building ‘opensensmapr_0.3.1.tar.gz’

Setting env vars --------------------------------------------------------------
_R_CHECK_CRAN_INCOMING_USE_ASPELL_: TRUE
_R_CHECK_CRAN_INCOMING_           : FALSE
_R_CHECK_FORCE_SUGGESTS_          : FALSE
Checking opensensmapr ---------------------------------------------------------
'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \
  CMD check '/tmp/RtmpJYeaXj/opensensmapr_0.3.1.tar.gz' --as-cran --timings  \
  --no-manual 

* using log directory ‘/home/daniel/git/o2r/opensensmapr.Rcheck’
* using R version 3.4.3 (2017-11-30)
* using platform: x86_64-pc-linux-gnu (64-bit)
* using session charset: UTF-8
* using options ‘--no-manual --as-cran’
* checking for file ‘opensensmapr/DESCRIPTION’ ... OK
* checking extension type ... Package
* this is package ‘opensensmapr’ version ‘0.3.1’
* package encoding: UTF-8
* checking package namespace information ... OK
* checking package dependencies ... OK
* checking if this is a source package ... OK
* checking if there is a namespace ... OK
* checking for executable files ... OK
* checking for hidden files and directories ... OK
* checking for portable file names ... OK
* checking for sufficient/correct file permissions ... OK
* checking whether package ‘opensensmapr’ can be installed ... OK
* checking installed package size ... OK
* checking package directory ... OK
* checking ‘build’ directory ... OK
* checking DESCRIPTION meta-information ... OK
* checking top-level files ... NOTE
File
  LICENSE
is not mentioned in the DESCRIPTION file.
Non-standard file/directory found at top level:
  ‘CHANGES.md’
* checking for left-over files ... OK
* checking index information ... OK
* checking package subdirectories ... OK
* checking R files for non-ASCII characters ... OK
* checking R files for syntax errors ... OK
* checking whether the package can be loaded ... OK
* checking whether the package can be loaded with stated dependencies ... OK
* checking whether the package can be unloaded cleanly ... OK
* checking whether the namespace can be loaded with stated dependencies ... OK
* checking whether the namespace can be unloaded cleanly ... OK
* checking loading without being on the library search path ... OK
* checking dependencies in R code ... WARNING
'::' or ':::' import not declared from: ‘maps’
'library' or 'require' call not declared from: ‘maps’
'loadNamespace' or 'requireNamespace' calls not declared from:
  ‘maps’ ‘maptools’ ‘rgeos’
'library' or 'require' call to ‘maps’ in package code.
  Please use :: or requireNamespace() instead.
  See section 'Suggested packages' in the 'Writing R Extensions' manual.
Unexported object imported by a ':::' call: ‘sf:::st_as_sf.data.frame’
  See the note in ?`:::` about the use of this operator.
* checking S3 generic/method consistency ... OK
* checking replacement functions ... OK
* checking foreign function calls ... OK
* checking R code for possible problems ... NOTE
plot.osem_measurements: no visible global function definition for ‘par’
plot.sensebox: no visible global function definition for ‘par’
plot.sensebox: no visible global function definition for ‘legend’
Undefined global functions or variables:
  legend par
Consider adding
  importFrom("graphics", "legend", "par")
to your NAMESPACE file.
* checking Rd files ... OK
* checking Rd metadata ... OK
* checking Rd line widths ... OK
* checking Rd cross-references ... WARNING
Missing link or links in documentation object 'opensensmapr.Rd':
  ‘sf’

See section 'Cross-references' in the 'Writing R Extensions' manual.

* checking for missing documentation entries ... WARNING
Vignette-only dependencies should go into Suggests:.
Do you plan a release on CRAN? I'd be happy to help.
sensebox / opensensmapR

make shure R CMD check does not error #9
