Running examples in 'classyfireR-Ex.R' failed
The error most likely occurred in:

> ### Name: get_classification
> ### Title: Get Entity Classification
> ### Aliases: get_classification
> 
> ### ** Examples
> 
> 
> # Valid InChI key where all four classification levels are available
> get_classification('BRMWTNUJHUMWMS-LURJTMIESA-N')
v BRMWTNUJHUMWMS-LURJTMIESA-N
# A tibble: 7 x 3
  Level      Classification                       CHEMONT          
  <chr>      <chr>                                <chr>            
1 kingdom    Organic compounds                    CHEMONTID:0000000
2 superclass Organic acids and derivatives        CHEMONTID:0000264
3 class      Carboxylic acids and derivatives     CHEMONTID:0000265
4 subclass   Amino acids, peptides, and analogues CHEMONTID:0000013
5 level 5    Amino acids and derivatives          CHEMONTID:0000347
6 level 6    Alpha amino acids and derivatives    CHEMONTID:0000060
7 level 7    Histidine and derivatives            CHEMONTID:0004311
> 
> # Valid InChI key where only three classification levels are available
> get_classification('MDHYEMXUFSJLGV-UHFFFAOYSA-N')
v MDHYEMXUFSJLGV-UHFFFAOYSA-N
# A tibble: 3 x 3
  Level      Classification                      CHEMONT          
  <chr>      <chr>                               <chr>            
1 kingdom    Organic compounds                   CHEMONTID:0000000
2 superclass Benzenoids                          CHEMONTID:0002448
3 class      Benzene and substituted derivatives CHEMONTID:0002279
> 
> # Invalid InChI key
> get_classification('MDHYEMXUFSJLGV-UHFFFAOYSA-B')
> 
> 
> # Using `dplyr` a vector of InChI Keys can be submitted and easily parsed
>   library(dplyr)

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

>   library(purrr)

Attaching package: 'purrr'

The following object is masked from 'package:magrittr':

    set_names

>   library(tidyr)

Attaching package: 'tidyr'

The following object is masked from 'package:magrittr':

    extract

> 
>  keys <- c(
+ 'BRMWTNUJHUMWMS-LURJTMIESA-N',
+ 'XFNJVJPLKCPIBV-UHFFFAOYSA-N',
+ 'TYEYBOSBBBHJIV-UHFFFAOYSA-N',
+ 'AFENDNXGAFYKQO-UHFFFAOYSA-N',
+ 'WHEUWNKSCXYKBU-QPWUGHHJSA-N',
+ 'WHBMMWSBFZVSSR-GSVOUGTGSA-N')
> 
>  classification_list <- map(keys, get_classification)
v AFENDNXGAFYKQO-UHFFFAOYSA-N
v WHEUWNKSCXYKBU-QPWUGHHJSA-N
v WHBMMWSBFZVSSR-GSVOUGTGSA-N
> 
>  classification_list <- map(classification_list, ~{select(.,-CHEMONT)})
Error in UseMethod("select_") : 
  no applicable method for 'select_' applied to an object of class "NULL"
Calls: map -> .f -> select -> select.default -> select_
Execution halted