constructor(config, traceAggregator, eventAggregator, metrics) {
    this.config = config
    this.traceAggregator = traceAggregator
    this.eventAggregator = eventAggregator
    this.metrics = metrics

    this.seenObjectsByTransaction = Object.create(null)
    this.seenStringsByTransaction = Object.create(null)

    this.traceAggregator.on('starting_data_send-error_data', this._onSendErrorTrace.bind(this))

    this.errorGroupCallback = null
  }
ErrorCollector is responsible for collecting JS errors and errored-out HTTP
transactions, and for converting them to error traces and error events expected
by the collector.

@private
@class