Underscores in numbers show as error

[SackCastellon]

When writing a number with underscores, these are masked as errors:

main() ->
  X = 1_234.333_333,
  io:format("~p\n", [X]).

However this code compiles and they are mentioned in the documentation:

Single underscore _ can be inserted between digits as a visual separator.

See: Erlang -- Data Types