bug in SGR loop w.r.t empty SGR parameters

[jamosdev]

I suggest to delete the break and make case -1 fall through to case 0

compare this kind of sequence on libtsm powered terminal vs others

\x1b[37;100;1m
\x1b[;90m
\x1b[J 

making this change fixed the issue (i noticed it on a kind of hard to explain issue triggered by fish terminal auto completion highlight flash)