On importing TruffleProvider from @harmony-js/core and :
const newAcc = truffleProvider.addByPrivateKey(process.env.TESTNET_PRIVATE_KEY);
generates the following error:

To reproduce:
- Use any project using
@harmony-js/core
- Remove
node_modules
- Reinstall
node_modules
- Rerun your project.
Note: The private key in the picture is from Ganache Testing. But the same error is occurring for different networks with original keys.