Feature: Display error if email in use (#4011)

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## Because
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Provides the user with visual feedback when an email they have entered
is already in use.

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- Add `status: :unprocessable_entity` to line 11 of
profiles_controller.rb

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Closes #3984 

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app/controllers/users/profiles_controller.rb

@@ -8,7 +8,7 @@ def update
       if current_user.update(user_params)
         redirect_to edit_users_profile_path, notice: 'Your account has been updated'
       else
-        render :edit
+        render :edit, status: :unprocessable_entity
       end
     end