Server error when updating configuration on Custom styles without content

[PierreMesure]

Describe the bug

When clicking on the button Update configuration on the Custom styles tab without any custom styles, I get a server error.

See stacktrace:

NoMethodError (undefined method `with_indifferent_access' for nil:NilClass):
  
rectify (0.13.0) lib/rectify/form.rb:54:in `hash_from'
rectify (0.13.0) lib/rectify/form.rb:11:in `from_params'
decidim-module-decidim_awesome (658d226e9ed1) app/forms/decidim/decidim_awesome/admin/config_form.rb:35:in `from_params'
decidim (5455ffe38454) decidim-core/app/controllers/concerns/decidim/form_factory.rb:65:in `from_params'
decidim-module-decidim_awesome (658d226e9ed1) app/controllers/decidim/decidim_awesome/admin/config_controller.rb:26:in `update'
actionpack (6.0.5) lib/action_controller/metal/basic_implicit_render.rb:6:in `send_action'
actionpack (6.0.5) lib/abstract_controller/base.rb:195:in `process_action'
actionpack (6.0.5) lib/action_controller/metal/rendering.rb:30:in `process_action'
actionpack (6.0.5) lib/abstract_controller/callbacks.rb:42:in `block in process_action'
activesupport (6.0.5) lib/active_support/callbacks.rb:112:in `block in run_callbacks'
activesupport (6.0.5) lib/active_support/core_ext/time/zones.rb:66:in `use_zone'
decidim (5455ffe38454) decidim-core/app/controllers/concerns/decidim/use_organization_time_zone.rb:21:in `use_organization_time_zone'
activesupport (6.0.5) lib/active_support/callbacks.rb:121:in `block in run_callbacks'
i18n (1.10.0) lib/i18n.rb:328:in `with_locale'
decidim (5455ffe38454) decidim-core/app/controllers/concerns/decidim/locale_switcher.rb:24:in `switch_locale'
activesupport (6.0.5) lib/active_support/callbacks.rb:121:in `block in run_callbacks'
activesupport (6.0.5) lib/active_support/callbacks.rb:139:in `run_callbacks'
actionpack (6.0.5) lib/abstract_controller/callbacks.rb:41:in `process_action'
actionpack (6.0.5) lib/action_controller/metal/rescue.rb:22:in `process_action'
actionpack (6.0.5) lib/action_controller/metal/instrumentation.rb:33:in `block in process_action'
activesupport (6.0.5) lib/active_support/notifications.rb:180:in `block in instrument'
activesupport (6.0.5) lib/active_support/notifications/instrumenter.rb:24:in `instrument'
activesupport (6.0.5) lib/active_support/notifications.rb:180:in `instrument'
actionpack (6.0.5) lib/action_controller/metal/instrumentation.rb:32:in `process_action'
actionpack (6.0.5) lib/action_controller/metal/params_wrapper.rb:245:in `process_action'
activerecord (6.0.5) lib/active_record/railties/controller_runtime.rb:27:in `process_action'
actionpack (6.0.5) lib/abstract_controller/base.rb:136:in `process'
actionview (6.0.5) lib/action_view/rendering.rb:39:in `process'
actionpack (6.0.5) lib/action_controller/metal.rb:190:in `dispatch'
actionpack (6.0.5) lib/action_controller/metal.rb:254:in `dispatch'
actionpack (6.0.5) lib/action_dispatch/routing/route_set.rb:50:in `dispatch'
actionpack (6.0.5) lib/action_dispatch/routing/route_set.rb:33:in `serve'
actionpack (6.0.5) lib/action_dispatch/journey/router.rb:49:in `block in serve'
actionpack (6.0.5) lib/action_dispatch/journey/router.rb:32:in `each'
actionpack (6.0.5) lib/action_dispatch/journey/router.rb:32:in `serve'
actionpack (6.0.5) lib/action_dispatch/routing/route_set.rb:834:in `call'
railties (6.0.5) lib/rails/engine.rb:527:in `call'

To Reproduce
Steps to reproduce the behavior:

1. Go to /admin/decidim_awesome/config/styles
2. Click on Update configuration
3. See a message There was a problem with our server.

Expected behavior

Clicking on this button when there is no content is useless so this is very low priority. But I'm expecting this button to be disabled or the behaviour to be nothing. In any case, no crash.

Desktop (please complete the following information):

• Version: Decidim 0.25.2, Decidim_Awesome 0.8.3