Module development and code questions

Hello

I'm coming from Drupal 8.7, through 8.9 and I'm now in 9.3

Since D 8.7 I'm repeatedly getting this error whose I like to get rid of. I see it on every page request and it pollutes very much my watchdog. It doesn't seem harming anything though.

I've not the beginning of a clue and  couldn't find anything  that can help on Google.
If someone knows how to solve it or how at least remove this error from filling up my watchdog...

Hi,

I need to send push notification when a content is added to a group.
I just install firebase module,
I see how to send a push message, but I can't see how to get the user's token.

I am using the states on a field of a content type but I get this error

I have the following in my mymodule.libraries.yml:

user:
  version: 1.12
  js:
    js/set-office-name.js: {}
    js/password.js: {}
  css:
    component:
      css/bnc-user.css: { minified: false }

contact_log:
  version: 1.12
  js:
    js/set-office-name.js: {}
    js/enable-district-office.js: {}
  css:
    component:
      css/bnc-user.css: { minified: false }

In my module.modules I have two hook_form_alter functions where I set the libraries used:

1) mymodule_form_node_bnc_message_form_alter:

I’m trying to setup a custom module which clones the content from NODETYPE_A to NODETYPE_B. For most part, both nodetypes use the same fields, but NODETYPE_B has a few additional ones. For example:

NODETYPE_A:
- Title (title)
- Body (body)
- Date (field_date_agenda)

NODETYPE_B:
- Title (title)
- Body (body)
- Date (field_date_agenda)
- Number of items (field_int_how_many)
- Reference to NodeTypeA (field_noderef_nta)

In older php days, when I got stuck developing code, I would just output some things to the screen.

That's isn't possible anymore with all the layers.

How do you look into objects?

Do you write things to a text file or are there other tricks?

For example, I'm in the middle of some code and I want to look into $responsive_image_style->getKeyedImageStyleMappings();

How can I have a look at what's inside?