Aggregation error - nil can't be coerced into Fixnum

Elastic Stack Logstash
11

Nothing will trigger the aggregation being pushed as an event in that case. I think the minimum that will work is below. I created a file that contains

{ "INCIDENTE" : 0 }

Then I run with this configuration

input { file { path => "/home/user/foo.json" sincedb_path => "/dev/null" start_position => "beginning" } }
filter {
    json { source => "message" }
    aggregate {
                task_id => "%{INCIDENTE}"
                code => "
                     map['JustTesting'] ||= 0; map['JustTesting'] += 1
                "
                push_map_as_event_on_timeout => true
                inactivity_timeout => 2

     }
}
output { stdout { codec => rubydebug } }

Using a file input is important, because if you a generator the pipeline will stop executing, and there will be no thread running that can execute the timeout code. That config gets me

[2019-02-20T17:09:24,994][INFO ][logstash.agent           ] Pipelines running {:count=>1, :running_pipelines=>[:main], :non_running_pipelines=>[]}
{
    "@timestamp" => 2019-02-20T22:09:24.992Z,
     "INCIDENTE" => 0,
          "path" => "/home/user/foo.json",
       "message" => "{ \"INCIDENTE\" : 0 }",
      "@version" => "1"
}
{
     "@timestamp" => 2019-02-20T22:09:30.075Z,
    "JustTesting" => 1,
       "@version" => "1"
}

If on the other hand I use a generator input

input { generator { count => 1 message => '{ "INCIDENTE" : 0 }' } }

Then with that same filter I get

[2019-02-20T17:14:15,587][INFO ][logstash.agent           ] Pipelines running {:count=>1, :running_pipelines=>[:main], :non_running_pipelines=>[]}
{
    "@timestamp" => 2019-02-20T22:14:15.565Z,
      "sequence" => 0,
     "INCIDENTE" => 0,
       "message" => "{ \"INCIDENTE\" : 0 }",
      "@version" => "1"
}
[2019-02-20T17:14:15,734][INFO ][logstash.pipeline        ] Pipeline has terminated {:pipeline_id=>"main", :thread=>"#<Thread:0x3765a362 run>"}

with no aggregation.