How to solve error: sending a transaction requires a signer (operation="sendtransaction", code=unsupported_operation, version=contracts/5.5.0)

This is quite a common issue for beginning Web 3 developers: sending a transaction requires a signer (operation="sendtransaction", code=unsupported_operation, version=contracts/5.5.0) When interacting with Smart Contracts on the Ethereum Blockchain...