replace.md
In stringr: Simple, Consistent Wrappers for Common String Operations

replacement must be a string

Code
  str_replace("x", "x", 1)
Condition
  Error in `str_replace()`:
  ! `replacement` must be a character vector, not the number 1.

can't replace empty/boundary

Code
  str_replace("x", "", "")
Condition
  Error in `str_replace()`:
  ! `pattern` can't be the empty string (`""`).
Code
  str_replace("x", boundary("word"), "")
Condition
  Error in `str_replace()`:
  ! `pattern` can't be a boundary.
Code
  str_replace_all("x", "", "")
Condition
  Error in `str_replace_all()`:
  ! `pattern` can't be empty.
Code
  str_replace_all("x", boundary("word"), "")
Condition
  Error in `str_replace_all()`:
  ! `pattern` can't be a boundary.

backrefs are correctly translated

Code
  str_replace_all("abcde", "(b)(c)(d)", "\\4")
Condition
  Error in `stri_replace_all_regex()`:
  ! Trying to access the index that is out of bounds. (U_INDEX_OUTOFBOUNDS_ERROR)