async function looksLikePostgresConnectionString(connectionString = null) {
  if (!connectionString || !connectionString.startsWith("postgresql://"))
    return "Invalid Postgres connection string. Must start with postgresql://";
  if (connectionString.includes(" "))
    return "Invalid Postgres connection string. Must not contain spaces.";
  return null;
}
Validates the Postgres connection string for the PGVector options.
@param {string} input - The Postgres connection string to validate.
@returns {string} - An error message if the connection string is invalid, otherwise null.