src/language-graphql/parser-graphql.js/fallbackParser
function fallbackParser(parse, source) {
  const parserOptions = {
    allowLegacySDLImplementsInterfaces: false,
    experimentalFragmentVariables: true,
  };
  try {
    return parse(source, parserOptions);
  } catch (_) {
    parserOptions.allowLegacySDLImplementsInterfaces = true;
    return parse(source, parserOptions);
  }
}