Add Task generic has error

Problem/Motivation

There is an "Add Task" button from the /burndown/task route but clicking it results in a whitescreen

#0 [internal function]: Drupal\burndown\Form\TaskForm->buildForm(Array, Object(Drupal\Core\Form\FormState))
#1 /var/www/drupal/web/core/lib/Drupal/Core/Form/FormBuilder.php(559): call_user_func_array(Array, Array)
#2 /var/www/drupal/web/core/lib/Drupal/Core/Form/FormBuilder.php(299): Drupal\Core\Form\FormBuilder->retrieveForm('burndown_task_t...', Object(Drupal\Core\Form\FormState))
#3 /var/www/drupal/web/core/lib/Drupal/Core/Controller/FormController.php(73): Drupal\Core\Form\FormBuilder->buildForm(Object(Drupal\burndown\Form\TaskForm), Object(Drupal\Core\Form\FormState))

The cause is the task/add form makes some assumptions about data and classes that are not there because they are only provided once the Task is associated to a project. (example: swimlanes and estimate size types)

My suggestion is that we remove this "Add Task" button from the /burndown/task route because it creates too many assumptive risks and task management chaos related to ending up with a task that is not fully connected to a project. Either that or we make the task/add form more defensive. But I can't think of a good reason why a task should be created while not in the context of a project. Currently this error is not often seen because the /burndown/task route is not revealed through menu or breadcrumb links. You can only get to it if you know it exists. #3605487: Burndown menu needs all lists represented

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes