dictionary names() and indexing methods broken in Windows

[kbenoit]

Seems related to #685 and also why the current master is broken on Windows.

The following fails on Windows.

testdict <- dictionary(file = "tests/data/dictionaries/issue-459.cat")
names(testdict)
## NULL
## Warning message:
## In class(x) <- class(x)[-i] :
##   Setting class(x) to "NA" sets attribute to NULL; result will no longer be an S4 object
testdict$SOUTH
## Error in sprintf(.subset2(x, "lookup_msg"), name) : 
##   'fmt' is not a character vector

testdict
## Dictionary object with 0 primary key entries and 2 nested levels.
## - SOUTH:
##   - BW:
##     - botswana, botswanan*, gaborone
##   - LS:
##     - lesotho, lesothonian*, maseru
##   - NA:
##     - namibia, namibian*, windhoek
##   - ZA:
##     - south africa, s african, sa, south african*, s african*, cape town, johannesburg
##   - SZ:
##     - swaziland, swazi*, lobamba, mbabane

On macOS, however:

testdict <- dictionary(file = "tests/data/dictionaries/issue-459.cat")
names(testdict)
## [1] "SOUTH"
testdict$SOUTH
## $BW
## $BW[[1]]
## [1] "botswana"   "botswanan*" "gaborone"  
## 
## 
## $LS
## $LS[[1]]
## [1] "lesotho"      "lesothonian*" "maseru"      
## 
## 
## $`NA`
## $`NA`[[1]]
## [1] "namibia"   "namibian*" "windhoek" 
## 
## 
## $ZA
## $ZA[[1]]
## [1] "south africa"   "s african"      "sa"             "south african*" "s african*"     "cape town"      "johannesburg"  
## 
## 
## $SZ
## $SZ[[1]]
## [1] "swaziland" "swazi*"    "lobamba"   "mbabane"  


testdict
## Dictionary object with 9 primary key entries and 2 nested levels.
## - CULTURE:
##   - people, war_in_iraq, civil_war
...

[koheiw]

I noticed that your dictionary object linked from #685 has NA in keys. I do not know how it happened yet, but it should not.

[kbenoit]

It's not a problem with NA, but rather a problem with the methods for indexing (called by the print method), I think. From Windows 10, R 3.4:

> simpledict <- dictionary(key1 = c("a", "b", "c*"), key2 = c("x", "y"), key3 = "z") 
> simpledict
Dictionary object with 3 key entries.
- key1:
  - a, b, c*
- key2:
  - x, y
- key3:
  - z
Warning message:
In class(x) <- class(x)[-i] :
  Setting class(x) to "NA" sets attribute to NULL; result will no longer be an S4 object
> simpledict2 <- dictionary(list(key1 = c("a", "b", "c*"), key2 = c("x", "y"), key3 = "z"))
> simpledict2
Dictionary object with 3 key entries.
- key1:
  - a, b, c*
- key2:
  - x, y
- key3:
  - z
Warning message:
In class(x) <- class(x)[-i] :
  Setting class(x) to "NA" sets attribute to NULL; result will no longer be an S4 object