async function getDatabase(url = undefined) {
  try {
    const response = await fetch(url || DATABASE_URL);
    const body = await response.text();
    return JSON5.parse(body);
  } catch (e) {
    if (e instanceof SyntaxError) {
      process.stderr.write(
        'Unable to parse the renamings database. Please ' +
          'report the issue at github.com/google/blockly/issues/new/choose\n',
      );
      process.exit();
    }
    throw e;
  }
}
Gets the database of renames.
@param {string=} url The URL to fetch the renamings database from, or
    undefined to fetch from master.
@returns {!Promise<!Object>} The database of renames as an object.