Summary:
When input string has non-finished markup tags or escaped tags,
eina_strbuf_append_length is called with Null string.
There is a Null checking in eina_strbuf_* API, but it will print error message when input string is Null.
Strictly speaking, *_markup_to_utf8 API could be used with any kind of input string.
So, we need to add Null checking for removing the useless error message.
Test Plan:
Call the API like the following code.
evas_textblock_text_markup_to_utf8(NULL, "test_text&&&&");
ERR message will be printed.
Reviewers: woohyun, tasn, seoz, Hermet, hbr4570
CC: cedric
Differential Revision: https://phab.enlightenment.org/D493