task expression function throws exception if task wasn't executed

The function "task" is throwing an exception instead of returning null in case the task wasn't executed.

I was expecting something like “<% task(task2) != null %>” to work but I get the following error:

YaqlEvaluationException: Can not evaluate YAQL expression: task(task2) , data = {u'__task_execution': {u'id': u'4ed41a94-47db-4a0a-841a-e0ee1147684e', u'name': u'task1'}, u'__env': {}, u'__execution': {u'id': u'94885e19-995b-4ae1-bdd5-c326f7093f92'}}; error: Failed to find task execution with name: task2

For the below workflow:

version: '2.0'

workflow_test:
  type: direct

  output:
    task2: <% task(task2) %>

  tasks:
    task1:
      action: std.noop
      on-success:
        - task2: <% false %>

    task2:
      action: std.noop

Renat: "it's a bug. This function needs to return null if not found. It happens because we use db_api.get_task_execution() instead of db_api.load_task_execution() internally."