Delta error while inserting code block

[willjayyyy]

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Steps for Reproduction

1. Visit [quilljs.com, jsfiddle.net, codepen.io]

2. Step Two I created an initial example and wrote a number 1 into the content

3. Step Three I format the content as code block and listen to text change to obtain delta

4. Step Four I combined the initial delta with the changed delta to regenerate the content, and found that the editor did not show any code blocks

The delta obtained using the getContents method is

[
    {
        "insert": "1"
    },
    {
        "attributes": {
            "code-block": "plain"
        },
        "insert": "\n"
    }
]

But the content I obtained by manually constructing delta is

{
    "ops": [
        {
            "retain": 1
        },
        {
            "retain": 1,
            "attributes": {
                "code-block": "plain"
            }
        }
    ]
}

Version: 2.0.2

Run Quill.version to find out

[willjayyyy]

The same problem still appears in the list