message: Fix tests
  I thought my last commit was innocuous, but that's always a dangerous attitude to have :)
  `Position.withColumn()` now does bounds checking, which the test framework wasn't too happy about
diff: @@ -129,7 +129,7 @@ class TestObjectHelper {
  for (let i = 0; i < lines.length; i++) {
  const columnIdx = lines[i].indexOf('|');
  if (columnIdx >= 0) {
  - ret.position = ret.position.withLine(i).withColumn(columnIdx);
  + ret.position = new Position(i, columnIdx);
  ret.success = true;
  }
  }
  