False positive UndetectableDelimiter error when parsing single-column CSV

[arberiii]

Description

When parsing a valid single-column CSV string, PapaParse reports an unnecessary UndetectableDelimiter warning, even though parsing succeeds and the delimiter is not ambiguous.

Example

const text = `id\n1\n2\n3`

Papa.parse(text, {
  complete: (results) => {
    console.log(results)
  },
  error: (error) => {
    console.error('Failed to parse CSV:', error)
  }
})

Actual behavior

The parsed results are correct, but the output also includes an error:

{
  "type": "Delimiter",
  "code": "UndetectableDelimiter",
  "message": "Unable to auto-detect delimiting character; defaulted to ','"
}

Expected behavior

For a single-column CSV with a valid header and data, PapaParse should not emit an UndetectableDelimiter error.
The defaulting behavior is fine internally, but this should not surface as an error in the results.