Me trying to understand what's going on with error rendering, fetching and so on in a Angular based project

What_the_error.coffee

# As I understand it
# 1. When Build is Finished - GET ERRORS FROM THE SERVER
# 2. Collect Errors for the whole build
# 3. Show those Errors
# 4. Allow to click on any error to make it disappear


# WHAT I FOUND SPLITTED INTO 2 FILES

# GLOBAL Variables
@allErrors = {}
@_errorListeners = []

# ON INITIATING
@build.addErrorListener(@addErrors.bind(this))

# -> add errors is a anonymous function that takes errors. We bind (this) to it
@addErrors = (errors) =>
  errors = errors.filter( (item) =>
    !@allErrors[item.type + item.msg]
  )
  errors.forEach( (item) =>
    @allErrors[item.type + item.msg] = true
  )
  @buildErrors = @buildErrors.concat(errors)

# ERROR LISTENERS ?
# The listener is the anonymous addErrros function
addErrorListener: (listener) ->
  @_errorListeners.push(listener) unless listener in @_errorListeners

# OKAY... now the ui is running somehow... we'll update the build status and process that
_processStatusResponse: (response) =>
  @setStatus(response.data.type)
  if @isFinished()
    @_fetchErrorList(@addErrors) # okay, if it's finishes. Call the fetch Errors function
  else
    setTimeout(@_fetchStatus, POLLING_INTERVAL)

# ->

_fetchErrorList: =>
  JetBuild.fetch.getData("#{@id()}/errors")
    .then(@_processErrorListResponse)
    .catch( =>
      setTimeout(@_fetchErrorList, POLLING_INTERVAL)
    )

# ->
_processErrorListResponse: (response) =>
  @dispatchErrors response.data.build_errors # why not put this in the above line ?

# ->
dispatchErrors: (errors) ->
  listener(errors) for listener in @_errorListeners


# Okay, then in the UI the errors get rendered at some point.
# They also have that click event bound to it
@onRemoveErrorMessage = (index) ->
  @buildErrors.splice(index, 1)[0]
  return

# THIS IS NEVER USED ..... WHYYYYYYYY
_addSystemError = (data, status) =>
  unless status == 404
    @addErrors [{
      type: "BUILD_ERROR_TYPE_SYSTEM",
      msg: "An error occurred on our server. Status: #{status}"
    }]