message: Make sure every token has a token.value string.
diff: @@ -50,6 +50,13 @@ exports.parse = function parse(source, options) {
  // We will reattach the tokens array to the file object below.
  delete ast.tokens;
  + // Make sure every token has a token.value string.
  + tokens.forEach(function (token) {
  + if (typeof token.value !== "string") {
  + token.value = lines.sliceString(token.loc.start, token.loc.end);
  + }
  + });
  +
  if (Array.isArray(ast.comments)) {
  comments = ast.comments;
  delete ast.comments;
  