The JsonReader allows JSON documents with missing comma in an array, e.g.

{
    "a" : [
        { "i" : 1}
        { "i" : 2}
    ]
}

The intention was likely to allow for extraneous trailing comma, e.g.

{
    "a" : [
        { "i" : 1},
        { "i" : 2},
    ]
}

which also succeeds, as it does in the shell.