code: void validateSignatureAlgorithmWithKey(JwtConsumerConfig config, Key key) throws InvalidClaimException {
  		String signatureAlgorithm = config.getSignatureAlgorithm();
  		if (key == null && signatureAlgorithm != null && !signatureAlgorithm.equalsIgnoreCase("none")) {
  			String msg = Tr.formatMessage(tc, "JWT_MISSING_KEY", new Object[] { signatureAlgorithm });
  			throw new InvalidClaimException(msg);
  		}
  	}
docs: Throws an exception if the provided key is null but the config specifies a
  signature algorithm other than "none".