Proposed resolution:

This wording is relative to N4582.

1. Change [fs.class.rec.dir.itr], class recursive_directory_iterator synopsis, as indicated:

   namespace std::filesystem {
     class recursive_directory_iterator {
     public:
       […]
       void pop();
       void pop(error_code& ec);
       void disable_recursion_pending();
       […]
     };
   }
   

2. Change [fs.rec.dir.itr.members] as indicated:

   void pop();
   void pop(error_code& ec);
   

   -30- Requires: *this != recursive_directory_iterator().

   -31- Effects: If depth() == 0, set *this to recursive_directory_iterator(). Otherwise, cease iteration of the directory currently being iterated over, and continue iteration over the parent directory.

   -?- Throws: As specified in Error reporting ([error.reporting]).

Unlike increment, pop() does not specify how it reports errors nor does it provide a std::error_code overload. However implementing pop() all but requires performing an increment, so it should handle errors in the same way.