Expressions: `{checkbox} notcontains 0` returns `false` even if the value is empty

[JaneSjs]

T26284 - Checkbox choices enable if logic
https://surveyjs.answerdesk.io/internal/ticket/details/T26284

---

Survey JSON definition:

{
  "pages": [
    {
      "name": "page1",
      "elements": [
        {
          "type": "expression",
          "name": "question2",
          "title": "{question1} notcontains 0",
          "expression": "{question1} notcontains 0"
        },
        {
          "type": "expression",
          "name": "question3",
          "startWithNewLine": false,
          "title": "{question1} notcontains 0",
          "expression": "{question1} notcontains '0'"
        },
        {
          "type": "checkbox",
          "name": "question1",
          "choices": [
            {
              "value": "0",
              "text": ""
            },
            {
              "value": "1",
              "text": ""
            },
            {
              "value": "2",
              "text": ""
            }
          ]
        }
      ]
    }
  ],
  "headerView": "advanced"
}

Current behavior: when question1 is empty, {question1} notcontains 0 returns false and {question1} notcontains '0' returns true.
Expected behavior: when question1 is empty, {question1} notcontains 0 returns true.