onTwoslashError returning string is ignored instead of replacing the code

[Karibash]

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Describe the bug

According to the JSDoc, if onTwoslashError returns a string, the returned string should replace the corresponding code block.
However, in the actual implementation, the returned string is ignored, and the code is not replaced.

Expected Behavior

The returned string should replace the code block where the error occurred, as documented in the JSDoc.

Actual Behavior

The returned string is ignored, and the original code remains unchanged.

Reproduction

none

Contributes

• I am willing to submit a PR to fix this issue
• I am willing to submit a PR with failing tests