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

> ### Name: envnames-package
> ### Title: Track user-defined environment names
> ### Aliases: envnames-package envnames
> ### Keywords: package environment
> 
> ### ** Examples
> 
> library(envnames)
> rm(list=ls())
> 
> ### Example 1: Retrieve the names of user-defined environments (created with new.env())
> # Create new environments
> env1 <- new.env()                      # Environment in .GlobalEnv
> env2 <- new.env()                      # Environment in .GlobalEnv
> env3 <- new.env(parent=baseenv())      # Environment whose enclosure or parent environment
>                                        # is the base environment
>                                        # (as opposed to the global environment)
> env_of_envs <- new.env()               # User-defined environment that contains other environments
> with(env_of_envs, env11 <- new.env()) # Environment defined inside environment env_of_envs
> 
> # Retrieve the environment name
> environment_name(env1)                       # named array with value "env1" and name "R_GlobalEnv"
             R_GlobalEnv package:envnames$testenv 
                  "env1"                   "env1" 
> environment_name(env3)                       # named array with value "env3" and name "R_GlobalEnv"
[1] "env3"
> environment_name(env9)                       # NULL (env9 does not exist)
NULL
> environment_name(env_of_envs)                # named array with value "env_of_envs" and name
[1] "env_of_envs"
>                                              # "R_GlobalEnv"
> # (2018/11/19) THE FOLLOWING IS AN IMPORTANT TEST BECAUSE IT TESTS THE CASE WHERE THE ADDRESS-NAME
> # LOOKUP TABLE CONTAINS ONLY ONE ROW (namely the row for the env11 environment present in
> # env_of_envs), WHICH CANNOT BE TESTED VIA TESTS USING THE testthat PACKAGE BECAUSE IN THAT CONTEXT
> # THE LOOKUP TABLE NEVER HAS ONLY ONE ROW!
> # (for more info about this limitation see the test commented out at the beginning of
> # test-get_env_names.r.
> environment_name(env11, envir=env_of_envs)   # "env11"
Error in as.data.frame.vector(x, ..., nm = nm) : 
  row names contain missing values
Calls: environment_name ... as.data.frame -> as.data.frame.character -> as.data.frame.vector
Execution halted