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": {
"NodeType": "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.