allow to resubmit form via shared link

app/controllers/start_form_controller.rb

@@ -13,12 +13,9 @@ class StartFormController < ApplicationController
   end
 
   def update
-    @submitter = Submitter.new(email: submitter_params[:email])
-
-    if params[:resubmit].blank?
-      @submitter = Submitter.where(submission: @template.submissions.where(deleted_at: nil))
-                            .find_by(email: submitter_params[:email]) || @submitter
-    end
+    @submitter = Submitter.where(submission: @template.submissions.where(deleted_at: nil))
+                          .then { |rel| params[:resubmit].present? ? rel.where(completed_at: nil) : rel }
+                          .find_or_initialize_by(**submitter_params.compact_blank)
 
     if @submitter.completed_at?
       redirect_to start_form_completed_path(@template.slug, email: submitter_params[:email])
@@ -50,7 +47,7 @@ class StartFormController < ApplicationController
   private
 
   def submitter_params
-    params.require(:submitter).permit(:email).tap do |attrs|
+    params.require(:submitter).permit(:email, :phone).tap do |attrs|
       attrs[:email] = Submissions.normalize_email(attrs[:email])
     end
   end