function pug_rethrow(err, filename, lineno, str) {
  if (!(err instanceof Error)) throw err;
  if ((typeof window != 'undefined' || !filename) && !str) {
    err.message += ' on line ' + lineno;
    throw err;
  }
  var context, lines, start, end;
  try {
    str = str || (__webpack_require__(900).readFileSync)(filename, {encoding: 'utf8'});
    context = 3;
    lines = str.split('\n');
    start = Math.max(lineno - context, 0);
    end = Math.min(lines.length, lineno + context);
  } catch (ex) {
    err.message +=
      ' - could not read from ' + filename + ' (' + ex.message + ')';
    pug_rethrow(err, null, lineno);
    return;
  }

  // Error context
  context = lines
    .slice(start, end)
    .map(function(line, i) {
      var curr = i + start + 1;
      return (curr == lineno ? '  > ' : '    ') + curr + '| ' + line;
    })
    .join('\n');

  // Alter exception message
  err.path = filename;
  try {
    err.message =
      (filename || 'Pug') +
      ':' +
      lineno +
      '\n' +
      context +
      '\n\n' +
      err.message;
  } catch (e) {}
  throw err;
}
Re-throw the given `err` in context to the
the pug in `filename` at the given `lineno`.

@param {Error} err
@param {String} filename
@param {String} lineno
@param {String} str original source
@api private