Behavior of `num_chars/2` is different that docs

Docs declare the following query: ``` ?- number_chars(X, "not_a_number"). error(syntax_error(cannot_parse_big_int),number_chars/2:0). ``` However when I run the same query on Scryer's master branch I get an error that mentions `end_of_file` instead: ``` ?- number_chars(X, "not_a_number"). error(syntax_error(unexpected_end_of_file),number_chars/2). ```