BlockNote AI table generation is unstable; long tables fail with ChunkExecutionError

Description

While using BlockNote AI to generate tables, I encountered two related issues.
Both issues are reproducible in the official AI Playground.

AI Playground:
https://www.blocknotejs.org/examples/ai/playground

Versions

{
  "@blocknote/core": "^0.45.0",
  "@blocknote/mantine": "^0.45.0",
  "@blocknote/react": "^0.45.0",
  "@blocknote/xl-ai": "^0.45.0"
}

Issue 1: Table generation is unreliable

Whenever the prompt asks the AI to generate a table, there is a non-deterministic failure rate.
Even for short tables, the AI sometimes fails immediately and shows an error instead of producing a table block.

Issue 2: Long tables fail during generation

When asking the AI to generate larger or longer tables (e.g. more rows or more content per cell), the generation process is interrupted and consistently fails.

Observed Error

ChunkExecutionError: Tool execution failed: Slice has openStart or openEnd > 0, but structure=false

Partial error object

{
  result: {
    error: ChunkExecutionError: Tool execution failed: Slice has openStart or openEnd > 0, but structure=false
  },
  chatStatus: "ready",
  chatError: undefined
}

The stack trace points to BlockNote’s internal transform / execute logic, suggesting a structural issue during streaming or chunk application.

Steps to Reproduce

1. Open the official BlockNote AI Playground
2. Enter a prompt asking the AI to generate a table
   • Short table (few rows): sometimes succeeds, sometimes errors
   • Long table (many rows / larger content): generation consistently fails mid-process
3. The table block is not fully created

Expected Behavior

• AI table generation should be stable or at least retryable
• Long tables should not break the ProseMirror document structure during streaming

Actual Behavior

• Table generation is unstable
• Long tables fail with a ChunkExecutionError and interrupt the generation process

Additional Notes

• Manual table insertion works correctly
• The issue only occurs when using BlockNote AI (@blocknote/xl-ai)
• This appears to be related to streaming chunk handling and incomplete table slice structure (structure=false)