Since libjson-c's json_object_get_int64() returns 0 for any input value
that has no integer representation, any kind of invalid array index
incorrectly yielded the first array element.

-- Testcase --
{%
	x = [1, 2, 3];

	print([
		x[1],
		x["1"],
		x[1.0],
		x[1.1],
		x.foo,
		x["foo"],
		x["0abc"],
		x[x],
		x[{ foo: true }]
	], "\n");
%}
-- End --

-- Expect stdout --
[ 2, 2, 2, null, null, null, null, null, null ]
-- End --