Convex + BlockNote fails with initialContent

[BleedingDev]

Describe the bug
Convex component for TipTap works for sync, but fails with loading initialContent.

Error

Error: initialContent must be a non-empty array of blocks, received: [object Object]
    at EditorContent (editor.tsx:40:18)
console.error	@	suppress-nextjs-warning.ts:15

Initial Content

{
    "type": "doc",
    "content": [
        {
            "type": "blockGroup",
            "content": [
                {
                    "type": "blockContainer",
                    "attrs": {
                        "id": "ae03b85c-f1df-45d8-821f-d6d5e175d7b6",
                        "textColor": "default",
                        "backgroundColor": "default"
                    },
                    "content": [
                        {
                            "type": "paragraph",
                            "attrs": {
                                "textAlignment": "left"
                            },
                            "content": [
                                {
                                    "type": "text",
                                    "text": "Tak co, budeme syncovat?"
                                }
                            ]
                        }
                    ]
                },
                {
                    "type": "blockContainer",
                    "attrs": {
                        "id": "fc4451aa-46cf-485e-b442-caa5d3d8894e",
                        "textColor": "default",
                        "backgroundColor": "default"
                    },
                    "content": [
                        {
                            "type": "heading",
                            "attrs": {
                                "textAlignment": "left",
                                "level": 1
                            },
                            "content": [
                                {
                                    "type": "text",
                                    "text": "Ale jak..."
                                }
                            ]
                        }
                    ]
                },
                {
                    "type": "blockContainer",
                    "attrs": {
                        "id": "5b6e4de4-be00-4f27-997e-1580014dc069",
                        "textColor": "default",
                        "backgroundColor": "default"
                    },
                    "content": [
                        {
                            "type": "paragraph",
                            "attrs": {
                                "textAlignment": "left"
                            },
                            "content": [
                                {
                                    "type": "text",
                                    "text": "naplníme původní obsah, když to nefunguje? 😭 "
                                }
                            ]
                        }
                    ]
                },
                {
                    "type": "blockContainer",
                    "attrs": {
                        "id": "8e7bbeea-c660-40a3-8593-cdecfb01df07",
                        "textColor": "default",
                        "backgroundColor": "default"
                    },
                    "content": [
                        {
                            "type": "paragraph",
                            "attrs": {
                                "textAlignment": "left"
                            }
                        }
                    ]
                }
            ]
        }
    ]
}

To Reproduce

1. Basic template for BlockNote.
2. Add Convex ProseMirror component to _extensions.
3. Add initialContent and observe broken app.

Expected outcome

Sync and initial content works well.

Current outcome

Sync works for the first time, but after page refresh it fails to load initialContent with error above.

Videos

No initialContent

Zaznam.obrazovky.2025-01-01.204540.mp4

Provided initialContent

Zaznam.obrazovky.2025-01-01.204842.mp4

Misc

• Node version: v22
• Package manager: pnpm
• Browser: Chrome or Edge