Can't some one explain to me where javascript is pulling this error message from?

[gregaryb]

1876  let g_arrayBooks = {};
1877  g_arrayBooks["3,16,154"] = [];
1878  g_arrayBooks[3,16,154].push({title:"Harry Potter & the Philosopher's Stone",author:"J.K.Rowling",price:"0000000010",quantity:"1",weight:"0000000200",summary:"The novel introduces readers to the magical world of Hogwarts School of Witchcraft and Wizardry and follows the adventures of a young boy named Harry Potter. Harry Potter is an orphan who has been living with his cruel and neglectful relatives, the Dursleys, ever since his parents were killed by the dark wizard Lord Voldemort when he was just a baby. On his eleventh birthday, Harry receives a letter from a mysterious messenger informing him that he is a wizard and has been accepted to attend Hogwarts.",image_filename:""});
	

Uncaught TypeError: can't access property "push", g_arrayBooks[154] is undefined

    <anonymous> https://www.katescastle.com.au/admin.php:1878

WTF?

'g_arrayBooks[154]' DOES NOT EXIST on line 1878!

 

[Ingolme]

The quotation marks are missing here

g_arrayBooks["3,16,154"].push