In `stringr` version 1.0.0, the following worked fine: ``` > str_replace(c(NA, "abc", ""), pattern = "^$", NA) [1] NA "abc" NA ``` In `stringr` version 1.1.0, an error is thrown: ``` > str_replace(c(NA, "abc", ""), pattern = "^$", NA) Error in if (char == "$") { : missing value where TRUE/FALSE needed ``` Is this updated behavior intentional?