async function testnet() {
  const connection = new AleoNetworkClient("https://api.explorer.aleo.org/v1/testnet");

  const latestHeight = await connection.getLatestHeight();
  console.log(`# latestHeight = `, latestHeight);

  const mappings = await connection.getProgramMappingNames("credits.aleo");
  console.log(`# mappings = `, mappings);

  const public_balance = await connection.getProgramMappingValue("credits.aleo", "account", "aleo10aju84jkxnvuw47qanfffnnzphwujsc803cqt6g237dq9a785qxq7zsqhf");
  console.log(`# balance = `, public_balance);

}

Error: Error fetching latest height.
Error: Error fetching program mappings - ensure the program exists on chain before trying again