[Bug]: Ordered lists produce "order":null in json and throw when consumed

[lehmamic]

What happened?

We have entries in the database containing an ordered list content with an order = null value:

"type": "ordered_list",
"attrs": {
    "order": null
},

We never processed those strings, they get stored straight of of the ngx-editor via Angular form control. I don't know whether it is valid to have a null value in this place or if its a bug. The problem is more when reading in this rtf json and displaying it within the ngx-editor again, it will throw an exception when the order is set to null.

ERROR RangeError: Expected value of type number for attribute order on type ordered_list, got null
    at st.validate (231.d37ef6056f1f65d5.js:1:219940)
    at Rt (231.d37ef6056f1f65d5.js:1:217090)
    at ot.checkAttrs (231.d37ef6056f1f65d5.js:1:218915)
    at F.fromJSON (231.d37ef6056f1f65d5.js:1:210012)
    at Ue.nodeFromJSON (231.d37ef6056f1f65d5.js:1:222338)
    at Array.map (<anonymous>)
    at ne.fromJSON (231.d37ef6056f1f65d5.js:1:196222)
    at F.fromJSON (231.d37ef6056f1f65d5.js:1:209935)
    at Ue.nodeFromJSON (231.d37ef6056f1f65d5.js:1:222338)
    at jt (231.d37ef6056f1f65d5.js:1:137

Version

v18.0.0

Angular Version

v18.2.13

What browsers are you seeing the problem on?

Firefox, Chrome, Safari

Link to reproduce

No response

Relevant log output

ERROR RangeError: Expected value of type number for attribute order on type ordered_list, got null
    at st.validate (231.d37ef6056f1f65d5.js:1:219940)
    at Rt (231.d37ef6056f1f65d5.js:1:217090)
    at ot.checkAttrs (231.d37ef6056f1f65d5.js:1:218915)
    at F.fromJSON (231.d37ef6056f1f65d5.js:1:210012)
    at Ue.nodeFromJSON (231.d37ef6056f1f65d5.js:1:222338)
    at Array.map (<anonymous>)
    at ne.fromJSON (231.d37ef6056f1f65d5.js:1:196222)
    at F.fromJSON (231.d37ef6056f1f65d5.js:1:209935)
    at Ue.nodeFromJSON (231.d37ef6056f1f65d5.js:1:222338)
    at jt (231.d37ef6056f1f65d5.js:1:137

Willing to submit a PR?

None

[MG-SNF]

This issue can be reproduced by entering "1." followed by a space and then text (e.g., "Test"). This automatically converts the input into a numbered list. However, the generated HTML is:

<ol start="NaN"><li><p>Test</p></li></ol>

In contrast, if we use the "Numbered List" option from the menu, the generated HTML is: <ol><li><p>Test</p></li></ol>

The presence of NaN in the attribute leads to a null value when converting to JSON:

"ordered_list",
      "attrs": {
        "order": null
      },
      "content": [
        {
          "type": "list_item",
          "content": [
            {
              "type": "paragraph",
              "attrs": {
                "align": null,
                "indent": null
              },
              "content": [
                {
                  "type": "text",
                  "text": "Test"
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}

See Example with "keyboard"

See Example with menu

You can try it on Stackblitz