grouping of arrays (-g) fails on empty arrays: `[]`

[trentm]

$ cat arrays.chunks
[
    {"one": 1}
]
[
    {"two": 2}
]
[]
[]

$ json -f arrays.chunks -g
json: error: input is not JSON: Syntax error at line 4, column 1:
        [
        ^
[
    {"one": 1}
]
[
    {"two": 2}
]
[]
[]

would be nice to support this.