feat: improve error highlighting to use precise ranges

[warcholjakub]

Summary

This PR introduces precise error highlighting. Errors are now displayed using their actual range instead of highlighting the entire line.

Key changes

• Errors are now highlighted using their actual range (startColumn/endColumn), not the entire line.
• Renamed LineMapper to PositionMapper, as instrumentation can shift both lines and columns. PositionMapper now maps both.
• Replaced all usages of Int => Int (from the old LineMapper) with Option[PositionMapper].
• Updated the Problem type: now includes severity, line, message, startColumn, and endColumn.
• Added and updated tests to verify column mapping in PositionMapperSpecs (formerly LineMapperSpecs).
• Refactored SBT and Scala-CLI runners and their tests to use the new PositionMapper and to assert precise error positions.
• Improved error handling for cases where error line is outside the document: such errors are now shown at the end of the last line.

Screenshots / GIFs

Before

After

[rochala]

Can this ever happen? Maybe lets throw here

[warcholjakub]

Good question 😅. I honestly can't remember what the use case for this was. I’m sure I had a reason, but from what I’ve tested now, I couldn’t reproduce this case.

[rochala]

maybe lets make it a tuple Option[(Int, Int)] ?

[warcholjakub]

I think Diagnostic requires a Double. Is this the solution you had in mind?

val preciseRangeOpt: Option[(Double, Double)] =
  if (problem.line.get > maxLine) {
    val endPos = lineInfo.to
    Some((endPos, endPos))
  } else {
    (problem.startColumn, problem.endColumn) match {
      case (Some(start), Some(end)) if start > 0 && end >= start =>
        val clampedStart = (start min (lineLength + 1)) max 1
        val clampedEnd = (end min (lineLength + 1)) max clampedStart
        Some((lineInfo.from + clampedStart - 1, lineInfo.from + clampedEnd - 1))
      case _ =>
        None
    }
  }

val (startColumn, endColumn) = preciseRangeOpt match {
  case Some((start, end)) =>
    (start, end)
  case None =>
    (lineInfo.from, lineInfo.to)
}