Fix accessing invalid memory when line is empty
Fix accessing invalid memory when line is empty

cwlin/libchewing,bbyykk/libtaigi,simonfork/libchewing,PingNote/libchewing,simonfork/libchewing,kito-cheng/libchewing,robert501128/libchewing,PeterDaveHello/libchewing,robert501128/libchewing,mangokingTW/libchewing,dimotsai/libchewing,PeterDaveHello/libchewing,cwlin/libchewing,PeterDaveHello/libchewing,ShengYenPeng/libchewing,dimotsai/libchewing,school510587/general_index_libchewing,kito-cheng/libchewing,bbyykk/libtaigi,bbyykk/libtaigi,czchen/libchewing,simonfork/libchewing,kito-cheng/libchewing,mangokingTW/libchewing,czchen/libchewing,dimotsai/libchewing,Chocobo1/libchewing,cwlin/libchewing,PingNote/libchewing,chewing/libchewing,Chocobo1/libchewing,Chocobo1/libchewing,school510587/general_index_libchewing,simonfork/libchewing,hiunnhue/libchewing,chewing/libchewing,Chocobo1/libchewing,PeterDaveHello/libchewing,hiunnhue/libchewing,bbyykk/libtaigi,PingNote/libchewing,mangokingTW/libchewing,school510587/general_index_libchewing,yan12125/libchewing,czchen/libchewing,bbyykk/libtaigi,czchen/libchewing,mangokingTW/libchewing,hiunnhue/libchewing,chewing/libchewing,PingNote/libchewing,hiunnhue/libchewing,Chocobo1/libchewing,chewing/libchewing,hiunnhue/libchewing,ShengYenPeng/libchewing,dimotsai/libchewing,yan12125/libchewing,ShengYenPeng/libchewing,school510587/general_index_libchewing,cwlin/libchewing,yan12125/libchewing,ShengYenPeng/libchewing,cwlin/libchewing,kito-cheng/libchewing,yan12125/libchewing,robert501128/libchewing,robert501128/libchewing