Return error tuple on unicode normalization functions

Prior to this patch, the normalization functions in the
unicode module would raise a function clause error for
non-utf8 binaries.

This patch changes it so it returns {error, SoFar, Invalid}
as characters_to_binary and characters_to_list does in
the unicode module.

Note string:next_codepoint/1 and string:next_grapheme had
to be changed accordingly and also return an error tuple.

0 files changed, 0 insertions, 0 deletions