[MC-59153] Books without tilte/author or too long title (>16) cause *Invalid book tag*

i'm trying to make a more complex book using json, it was working before snapshot 14w26a, but now it only show invalid book tag
command to give(part of it):

/give @a written_book 1 0 {resolved:0b,title:"Creative Helper",author:"HeroProNight",pages:["{\"text\":\"\",\"extra\":[{\"text\":\"keepInventory \",\"color\":\"dark_aqua\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/gamerule keepInventory\"},\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"keep inventory after death\"}}]}"]}