Log decoding error return codes

                    returncode = RET_CODE_TIMEOUT_EXP

                if returncode != 0:

                    fail_string = "Decoding {} to {} failed!"

                    fail_string = "Decoding {} to {} failed "

                    if returncode == RET_CODE_TIMEOUT_EXP:

                        fail_string = (

                            fail_string[:-1]

                            + f" due to timeout after {self.timeout} seconds!"

                        )

                        fail_string += f"due to timeout after {self.timeout} seconds"

                    else:

                        fail_string += f"with exit code {returncode}"

                    fail_string += "!"

                    self.logger.error(fail_string.format(enc_file_name, dec_file_name))

                    with self.lock: