auto_explain produces invalid JSON

The auto_explain module appears to create invalid JSON (in all versions
since 9.0). For example, with the settings

auto_explain.log_format = 'json'
auto_explain.log_min_duration = 0

the query

select * from pg_type;

produces this in the log:

LOG: duration: 529.808 ms plan:
[
"Query Text": "select * from pg_type;",
"Plan": {
"Node Type": "Seq Scan",
"Relation Name": "pg_type",
"Alias": "pg_type",
"Startup Cost": 0.00,
"Total Cost": 9.87,
"Plan Rows": 287,
"Plan Width": 611
}
]

Note that at the top level, it uses the array delimiters [ ] for what is
actually an object (key/value). Running this through a JSON parser will
fail.

By contrast, EXPLAIN (FORMAT JSON) on the command line produces:

QUERY PLAN
-----------------------------------
[
{
"Plan": {
"Node Type": "Seq Scan",
"Relation Name": "pg_type",
"Alias": "pg_type",
"Startup Cost": 0.00,
"Total Cost": 9.87,
"Plan Rows": 287,
"Plan Width": 611
}
}
]
(1 row)

So there is evidently something out of sync between what EXPLAIN and
what auto_explain produces.