Invalid user causes 500 on application submission creation

[werebus]

Had a user submit an application with the email address of "theirnetid@umass" (without the umass.edu) today which made the user invalid.

Here's the controller action:

jobapps/app/controllers/application_submissions_controller.rb

Lines 10 to 25 in 1b7342e

	def create
	create_user if @current_user.blank?
	data = ApplicationDataParser.new(params.require(:data)).result
	params.require :position_id
	record = ApplicationSubmission.create(record_params
	.merge(data: data,
	user: @current_user,
	reviewed: false))
	record.email_subscribers applicant: @current_user
	create_unavailability(record) if record.position.application_template.unavailability_enabled?
	show_message :application_receipt,
	default: 'Your application has been submitted. Thank you!'
	redirect_to student_dashboard_path
	end

• create_user tries to create a User, but fails silently, and @current_user ends up remaining nil
• ApplicationSubmission.create fails because it requires a user to be valid
• create_unavailability ends up calling record.create_unavailability, which raises an exception:

    An ActiveRecord::RecordNotSaved occurred in application_submissions#create:
    
    You cannot call create unless the parent is saved
      app/controllers/application_submissions_controller.rb:107:in `create_unavailability'

So, in the end, the user got a 500 error and no explanation of what they did wrong.

[werebus]

Duplicate of #338