Watcher execution error

Good day I have a problem running a watcher, I get an execution error.

{
  "watch_id": "_inlined_",
  "node": "ELuSGxpSRICZb2ZHJp4paA",
  "state": "failed",
  "user": "elastic",
  "status": {
    "state": {
      "active": true,
      "timestamp": "2020-10-14T21:13:06.143Z"
    },
    "actions": {
      "email_1": {
        "ack": {
          "timestamp": "2020-10-14T21:13:06.143Z",
          "state": "awaits_successful_execution"
        }
      }
    },
    "execution_state": "failed",
    "version": -1
  },
  "trigger_event": {
    "type": "manual",
    "triggered_time": "2020-10-14T21:13:06.143Z",
    "manual": {
      "schedule": {
        "scheduled_time": "2020-10-14T21:13:06.143Z"
      }
    }
  },
  "input": {
    "search": {
      "request": {
        "search_type": "query_then_fetch",
        "indices": [
          "agenteallot*"
        ],
        "rest_total_hits_as_int": true,
        "body": {
          "size": 0,
          "query": {
            "bool": {
              "filter": [
                {
                  "range": {
                    "@timestamp": {
                      "gte": "{{ctx.trigger.scheduled_time}}||-5m",
                      "lte": "{{ctx.trigger.scheduled_time}}",
                      "format": "strict_date_optional_time||basic_time_no_millis"
                    }
                  }
                },
                {
                  "term": {
                    "monitor.name.keyword": "01-1-CAV30328203-DATOS-PPAL-2.7G-99.98"
                  }
                }
              ]
            }
          },
          "aggs": {
            "metricAgg": {
              "max": {
                "field": "summary.up"
              }
            }
          }
        }
      }
    }
  },
  "condition": {
    "script": {
      "source": "ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;",
      "lang": "painless",
      "params": {
        "threshold": 0.8
      }
    }
  },
  "metadata": {
    "name": "Alerta caída enlace único2.2",
    "xpack": {
      "type": "json"
    }
  },
  "result": {
    "execution_time": "2020-10-14T21:13:06.143Z",
    "execution_duration": 496,
    "input": {
      "type": "search",
      "status": "success",
      "payload": {
        "_shards": {
          "total": 1,
          "failed": 0,
          "successful": 1,
          "skipped": 0
        },
        "hits": {
          "hits": [],
          "total": 5,
          "max_score": null
        },
        "took": 495,
        "timed_out": false,
        "aggregations": {
          "metricAgg": {
            "value": 1
          }
        }
      },
      "search": {
        "request": {
          "search_type": "query_then_fetch",
          "indices": [
            "agenteallot*"
          ],
          "rest_total_hits_as_int": true,
          "body": {
            "size": 0,
            "query": {
              "bool": {
                "filter": [
                  {
                    "range": {
                      "@timestamp": {
                        "gte": "2020-10-14T21:13:06.143647Z||-5m",
                        "lte": "2020-10-14T21:13:06.143647Z",
                        "format": "strict_date_optional_time||basic_time_no_millis"
                      }
                    }
                  },
                  {
                    "term": {
                      "monitor.name.keyword": "01-1-CAV30328203-DATOS-PPAL-2.7G-99.98"
                    }
                  }
                ]
              }
            },
            "aggs": {
              "metricAgg": {
                "max": {
                  "field": "summary.up"
                }
              }
            }
          }
        }
      }
    },
    "actions": []
  },
  "exception": {
    "type": "script_exception",
    "reason": "runtime error",
    "script_stack": [
      "arr = ctx.payload.aggregations.bucketAgg.buckets; ",
      "                                        ^---- HERE"
    ],
    "script": "ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;",
    "lang": "painless",
    "position": {
      "offset": 50,
      "start": 10,
      "end": 60
    },
    "caused_by": {
      "type": "null_pointer_exception",
      "reason": "Cannot invoke \"Object.getClass()\" because \"receiver\" is null",
      "stack_trace": "java.lang.NullPointerException: Cannot invoke \"Object.getClass()\" because \"receiver\" is null\n\tat org.elasticsearch.painless.DefBootstrap$PIC.checkClass(DefBootstrap.java:142)\n\tat org.elasticsearch.painless.PainlessScript$Script.execute(ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;:51)\n\tat org.elasticsearch.xpack.watcher.condition.ScriptCondition.doExecute(ScriptCondition.java:60)\n\tat org.elasticsearch.xpack.watcher.condition.ScriptCondition.execute(ScriptCondition.java:55)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService.executeInner(ExecutionService.java:512)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService.execute(ExecutionService.java:319)\n\tat org.elasticsearch.xpack.watcher.transport.actions.execute.TransportExecuteWatchAction$1.doRun(TransportExecuteWatchAction.java:159)\n\tat org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService$WatchExecutionTask.run(ExecutionService.java:626)\n\tat org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:636)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)\n\tat java.base/java.lang.Thread.run(Thread.java:832)\n"
    },
    "stack_trace": "ScriptException[runtime error]; nested: NullPointerException[Cannot invoke \"Object.getClass()\" because \"receiver\" is null];\n\tat org.elasticsearch.painless.PainlessScript.convertToScriptException(PainlessScript.java:96)\n\tat org.elasticsearch.painless.PainlessScript$Script.execute(ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;:93)\n\tat org.elasticsearch.xpack.watcher.condition.ScriptCondition.doExecute(ScriptCondition.java:60)\n\tat org.elasticsearch.xpack.watcher.condition.ScriptCondition.execute(ScriptCondition.java:55)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService.executeInner(ExecutionService.java:512)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService.execute(ExecutionService.java:319)\n\tat org.elasticsearch.xpack.watcher.transport.actions.execute.TransportExecuteWatchAction$1.doRun(TransportExecuteWatchAction.java:159)\n\tat org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)\n\tat org.elasticsearch.xpack.watcher.execution.ExecutionService$WatchExecutionTask.run(ExecutionService.java:626)\n\tat org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:636)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)\n\tat java.base/java.lang.Thread.run(Thread.java:832)\nCaused by: java.lang.NullPointerException: Cannot invoke \"Object.getClass()\" because \"receiver\" is null\n\tat org.elasticsearch.painless.DefBootstrap$PIC.checkClass(DefBootstrap.java:142)\n\tat org.elasticsearch.painless.PainlessScript$Script.execute(ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;:51)\n\t... 11 more\n"
  }
}

This is the watcher's source code:

{
  "trigger": {
    "schedule": {
      "interval": "1h"
    }
  },
  "input": {
    "search": {
      "request": {
        "search_type": "query_then_fetch",
        "indices": [
          "agenteallot*"
        ],
        "rest_total_hits_as_int": true,
        "body": {
          "size": 0,
          "query": {
            "bool": {
              "filter": [
                {
                  "range": {
                    "@timestamp": {
                      "gte": "{{ctx.trigger.scheduled_time}}||-5m",
                      "lte": "{{ctx.trigger.scheduled_time}}",
                      "format": "strict_date_optional_time||basic_time_no_millis"
                    }
                  }
                },
                {
                  "term": {
                    "monitor.name.keyword": "01-1-CAV30328203-DATOS-PPAL-2.7G-99.98"
                  }
                }
              ]
            }
          },
          "aggs": {
            "metricAgg": {
              "max": {
                "field": "summary.up"
              }
            }
          }
        }
      }
    }
  },
  "condition": {
    "script": {
      "source": "ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; for (int i = 0; i < arr.length; i++) { if (arr[i]['metricAgg'].value >= params.threshold) { return true; } } return false;",
      "lang": "painless",
      "params": {
        "threshold": 0.8
      }
    }
  },
  "actions": {
    "email_1": {
      "email": {
        "profile": "standard",
        "attach_data": {
          "format": "yaml"
        },
        "to": [
          "juan.jaramillo@megadvantage.com",
          "victor.vera@megadvantage.com"
        ],
        "subject": "{{ctx.metadata.name}} {{ctx.payload.results}}",
        "body": {
          "text": """Buen dia, Adjunto registro del reporte.

 ⚠️ALERTA NODO!!! El siguiente enlace perdió la conexión. 

 Estado: Down🔴 

 Nombre del Enlace: {{ctx.payload.results}} 

 🕧Hora: {{ctx.execution_time}}  {{ctx.result.execution_time}}

 Área: Networking 

 🔔Mensaje Alerta: El enlace ha dejado de responder. Responder correo a telecomunicaciones@udistrital.edu.co 

 Ingrese aquí para más información: https://72dfe17217744236af40cc31b704a664.us-central1.gcp.cloud.es.io:9243/s/distrital/app/uptime#"""
        }
      }
    }
  },
  "transform": {
    "script": {
      "source": "HashMap result = new HashMap(); ArrayList arr = ctx.payload.aggregations.bucketAgg.buckets; ArrayList filteredHits = new ArrayList(); for (int i = 0; i < arr.length; i++) { HashMap filteredHit = new HashMap(); filteredHit.key = arr[i].key; filteredHit.value = arr[i]['metricAgg'].value; if (filteredHit.value >= params.threshold) { filteredHits.add(filteredHit); } } result.results = filteredHits; return result;",
      "lang": "painless",
      "params": {
        "threshold": 0.8
      }
    }
  }
}

Thanks!